diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index 522cff4..b9c2547 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -13,267 +13,275 @@ permissions:
 
 jobs:
 
-#  vlucas-phpdotenv-php83-82-81-80:
-#
-#    name: "PHP${{ matrix.php }} vlucas/phpdotenv ${{ matrix.vlucas-phpdotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
-#    runs-on: "${{ matrix.os }}"
-#    strategy:
-#      fail-fast: false
-#      matrix:
-#        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
-#        php: [ "8.3", "8.2", "8.1", "8.0" ]
-#        vlucas-phpdotenv: [ "^5.0", "^4.1.5", "^3.6.4", "^2.0", "^1.0" ]
-#        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
-#        include:
-#          - php: "8.3"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.2"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.2"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.1"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.0"
-#            phpunit: "^9.3"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - os: "ubuntu-latest"
-#            os-title: "ubuntu"
-#          - os: "macos-latest"
-#            os-title: "macos"
-#          - os: "windows-latest"
-#            os-title: "win"
-#          - dependency-prefer: "prefer-stable"
-#            dependency-prefer-title: "stable"
-#          - dependency-prefer: "prefer-lowest"
-#            dependency-prefer-title: "lowest"
-#
-#    steps:
-#
-#      - name: "Checkout code"
-#        uses: "actions/checkout@v4"
-#
-#      - name: "Validate composer.json and composer.lock"
-#        run: "composer validate --strict"
-#
-#      - name: "Setup PHP"
-#        uses: "shivammathur/setup-php@v2"
-#        with:
-#          php-version: "${{ matrix.php }}"
-#          extensions: fileinfo, mbstring
-#          ini-values: error_reporting=E_ALL
-#          coverage: none
-#        env:
-#          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-#
-#      # find composer's cache directory - so we know which directory to cache in the next step
-#      - name: "Find composer's cache directory"
-#        id: "composer-cache"
-#        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
-#        run: |
-#          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
-#
-#      - name: "Cache composer's cache directory"
-#        uses: "actions/cache@v3"
-#        with:
-#          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
-#          key: "[${{ matrix.os }}][php-${{ matrix.php }}][vlucas/phpdotenv-${{ matrix.vlucas-phpdotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
-#
-#      - name: "Install dependencies"
-#        uses: "nick-fields/retry@v2"
-#        with:
-#          timeout_minutes: 5
-#          max_attempts: 5
-#          command: |
-#            composer remove "infection/infection" --dev --no-interaction --no-update
-#            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
-#            composer remove "squizlabs/php_codesniffer" --dev --no-interaction --no-update
-#            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#            composer require "vlucas/phpdotenv:${{ matrix.vlucas-phpdotenv }}" --dev --no-interaction --no-update
-#            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
-#
-#      - name: "Execute tests"
-#        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
-#
-#
-#
-#  vlucas-phpdotenv-php74-73-72-71-70:
-#
-#    name: "PHP${{ matrix.php }} vlucas/phpdotenv ${{ matrix.vlucas-phpdotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
-#    runs-on: "${{ matrix.os }}"
-#    strategy:
-#      fail-fast: false
-#      matrix:
-#        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
-#        php: [ "7.4", "7.3", "7.2", "7.1", "7.0" ]
-#        vlucas-phpdotenv: [ "^5.0", "^4.1.5", "^3.6.4", "^2.0", "^1.0" ]
-#        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
-#        include:
-#          - php: "7.4"
-#            phpunit: "^9.3"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - php: "7.3"
-#            phpunit: "^9.3"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - php: "7.2"
-#            phpunit: "^8.0"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - php: "7.1"
-#            phpunit: "^7.0"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - php: "7.0"
-#            phpunit: "^6.0"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - os: "ubuntu-latest"
-#            os-title: "ubuntu"
-#          - os: "macos-latest"
-#            os-title: "macos"
-#          - os: "windows-latest"
-#            os-title: "win"
-#          - dependency-prefer: "prefer-stable"
-#            dependency-prefer-title: "stable"
-#          - dependency-prefer: "prefer-lowest"
-#            dependency-prefer-title: "lowest"
-#        exclude:
-#          - php: "7.0"
-#            vlucas-phpdotenv: "^5.0"
-#
-#    steps:
-#
-#      - name: "Checkout code"
-#        uses: "actions/checkout@v4"
-#
-#      - name: "Validate composer.json and composer.lock"
-#        run: "composer validate --strict"
-#
-#      - name: "Setup PHP"
-#        uses: "shivammathur/setup-php@v2"
-#        with:
-#          php-version: "${{ matrix.php }}"
-#          extensions: fileinfo, mbstring
-#          ini-values: error_reporting=E_ALL
-#          coverage: none
-#        env:
-#          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-#
-#      # find composer's cache directory - so we know which directory to cache in the next step
-#      - name: "Find composer's cache directory"
-#        id: "composer-cache"
-#        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
-#        run: |
-#          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
-#
-#      - name: "Cache composer's cache directory"
-#        uses: "actions/cache@v3"
-#        with:
-#          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
-#          key: "[${{ matrix.os }}][php-${{ matrix.php }}][vlucas/phpdotenv-${{ matrix.vlucas-phpdotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
-#
-#      - name: "Install dependencies"
-#        uses: "nick-fields/retry@v2"
-#        with:
-#          timeout_minutes: 5
-#          max_attempts: 5
-#          command: |
-#            composer remove "infection/infection" --dev --no-interaction --no-update
-#            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
-#            composer remove "squizlabs/php_codesniffer" --dev --no-interaction --no-update
-#            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#            composer require "vlucas/phpdotenv:${{ matrix.vlucas-phpdotenv }}" --dev --no-interaction --no-update
-#            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
-#
-#      - name: "Execute tests"
-#        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
-#
-#
-#
-#  symfony-dotenv-php83-82-81-80:
-#
-#    name: "PHP${{ matrix.php }} symfony/dotenv ${{ matrix.symfony-dotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
-#    runs-on: "${{ matrix.os }}"
-#    strategy:
-#      fail-fast: false
-#      matrix:
-#        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
-#        php: [ "8.3", "8.2", "8.1", "8.0" ]
-#        symfony-dotenv: [ "^6.0", "^5.0", "^4.0", "^3.3" ]
-#        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
-#        include:
-#          - php: "8.3"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.2"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.2"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.1"
-#            phpunit: "^10.1.0"
-#            phpunit-config-file: "phpunit.github-actions.xml.dist"
-#          - php: "8.0"
-#            phpunit: "^9.3"
-#            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
-#          - os: "ubuntu-latest"
-#            os-title: "ubuntu"
-#          - os: "macos-latest"
-#            os-title: "macos"
-#          - os: "windows-latest"
-#            os-title: "win"
-#          - dependency-prefer: "prefer-stable"
-#            dependency-prefer-title: "stable"
-#          - dependency-prefer: "prefer-lowest"
-#            dependency-prefer-title: "lowest"
-#
-#    steps:
-#
-#      - name: "Checkout code"
-#        uses: "actions/checkout@v4"
-#
-#      - name: "Validate composer.json and composer.lock"
-#        run: "composer validate --strict"
-#
-#      - name: "Setup PHP"
-#        uses: "shivammathur/setup-php@v2"
-#        with:
-#          php-version: "${{ matrix.php }}"
-#          extensions: fileinfo, mbstring
-#          ini-values: error_reporting=E_ALL
-#          coverage: none
-#        env:
-#          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
-#
-#      # find composer's cache directory - so we know which directory to cache in the next step
-#      - name: "Find composer's cache directory"
-#        id: "composer-cache"
-#        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
-#        run: |
-#          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
-#
-#      - name: "Cache composer's cache directory"
-#        uses: "actions/cache@v3"
-#        with:
-#          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
-#          key: "[${{ matrix.os }}][php-${{ matrix.php }}][symfony/dotenv-${{ matrix.symfony-dotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
-#
-#      - name: "Install dependencies"
-#        uses: "nick-fields/retry@v2"
-#        with:
-#          timeout_minutes: 5
-#          max_attempts: 5
-#          command: |
-#            composer remove "infection/infection" --dev --no-interaction --no-update
-#            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
-#            composer remove "squizlabs/php_codesniffer" --dev --no-interaction --no-update
-#            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#            composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" --dev --no-interaction --no-update
-#            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
-#
-#      - name: "Execute tests"
-#        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
+  vlucas-phpdotenv-php83-82-81-80:
+
+    name: "PHP${{ matrix.php }} vlucas/phpdotenv ${{ matrix.vlucas-phpdotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
+    runs-on: "${{ matrix.os }}"
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
+        php: [ "8.3", "8.2", "8.1", "8.0" ]
+        vlucas-phpdotenv: [ "^5.0", "^4.1.5", "^3.6.4", "^2.0", "^1.1.0" ]
+        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
+        include:
+          - php: "8.3"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.2"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.2"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.1"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.0"
+            phpunit: "^9.3"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - os: "ubuntu-latest"
+            os-title: "ubuntu"
+          - os: "macos-latest"
+            os-title: "macos"
+          - os: "windows-latest"
+            os-title: "win"
+          - dependency-prefer: "prefer-stable"
+            dependency-prefer-title: "stable"
+          - dependency-prefer: "prefer-lowest"
+            dependency-prefer-title: "lowest"
+
+    steps:
+
+      - name: "Checkout code"
+        uses: "actions/checkout@v4"
+
+      - name: "Validate composer.json and composer.lock"
+        run: "composer validate --strict"
+
+      - name: "Setup PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          php-version: "${{ matrix.php }}"
+          extensions: fileinfo, mbstring
+          ini-values: error_reporting=E_ALL
+          coverage: none
+        env:
+          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+
+      # find composer's cache directory - so we know which directory to cache in the next step
+      - name: "Find composer's cache directory"
+        id: "composer-cache"
+        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
+        run: |
+          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
+
+      - name: "Cache composer's cache directory"
+        uses: "actions/cache@v3"
+        with:
+          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
+          key: "[${{ matrix.os }}][php-${{ matrix.php }}][vlucas/phpdotenv-${{ matrix.vlucas-phpdotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
+
+      - name: "Install dependencies"
+        uses: "nick-fields/retry@v2"
+        with:
+          timeout_minutes: 5
+          max_attempts: 5
+          shell: bash # make sure "^" characters are interpreted properly on Windows (e.g. in "^5.0")
+          command: |
+            composer remove "infection/infection" --dev --no-interaction --no-update
+            composer remove "phpcsstandards/php_codesniffer" --dev --no-interaction --no-update
+            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
+            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
+            composer require "vlucas/phpdotenv:${{ matrix.vlucas-phpdotenv }}" --dev --no-interaction --no-update
+            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
+
+      - name: "Execute tests"
+        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
+
+
+
+  vlucas-phpdotenv-php74-73-72-71-70:
+
+    name: "PHP${{ matrix.php }} vlucas/phpdotenv ${{ matrix.vlucas-phpdotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
+    runs-on: "${{ matrix.os }}"
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
+        php: [ "7.4", "7.3", "7.2", "7.1", "7.0" ]
+        vlucas-phpdotenv: [ "^5.0", "^4.1.5", "^3.6.4", "^2.0", "^1.1.0" ]
+        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
+        include:
+          - php: "7.4"
+            phpunit: "^9.3"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - php: "7.3"
+            phpunit: "^9.3"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - php: "7.2"
+            phpunit: "^8.0"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - php: "7.1"
+            phpunit: "^7.0"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - php: "7.0"
+            phpunit: "^6.0"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - os: "ubuntu-latest"
+            os-title: "ubuntu"
+          - os: "macos-latest"
+            os-title: "macos"
+          - os: "windows-latest"
+            os-title: "win"
+          - dependency-prefer: "prefer-stable"
+            dependency-prefer-title: "stable"
+          - dependency-prefer: "prefer-lowest"
+            dependency-prefer-title: "lowest"
+        exclude:
+          - php: "7.0"
+            vlucas-phpdotenv: "^5.0"
+
+    steps:
+
+      - name: "Checkout code"
+        uses: "actions/checkout@v4"
+
+      - name: "Validate composer.json and composer.lock"
+        run: "composer validate --strict"
+
+      - name: "Setup PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          php-version: "${{ matrix.php }}"
+          extensions: fileinfo, mbstring
+          ini-values: error_reporting=E_ALL
+          coverage: none
+        env:
+          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+
+      # find composer's cache directory - so we know which directory to cache in the next step
+      - name: "Find composer's cache directory"
+        id: "composer-cache"
+        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
+        run: |
+          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
+
+      - name: "Cache composer's cache directory"
+        uses: "actions/cache@v3"
+        with:
+          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
+          key: "[${{ matrix.os }}][php-${{ matrix.php }}][vlucas/phpdotenv-${{ matrix.vlucas-phpdotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
+
+      - name: "Install dependencies"
+        uses: "nick-fields/retry@v2"
+        with:
+          timeout_minutes: 5
+          max_attempts: 5
+          shell: bash # make sure "^" characters are interpreted properly on Windows (e.g. in "^5.0")
+          command: |
+            composer remove "infection/infection" --dev --no-interaction --no-update
+            composer remove "phpcsstandards/php_codesniffer" --dev --no-interaction --no-update
+            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
+            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
+            composer require "vlucas/phpdotenv:${{ matrix.vlucas-phpdotenv }}" --dev --no-interaction --no-update
+            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
+
+      - name: "Execute tests"
+        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
+
+
+
+  symfony-dotenv-php83-82-81-80:
+
+    name: "PHP${{ matrix.php }} symfony/dotenv ${{ matrix.symfony-dotenv }} ${{ matrix.os-title }} ${{ matrix.dependency-prefer-title }}"
+    runs-on: "${{ matrix.os }}"
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
+        php: [ "8.3", "8.2", "8.1", "8.0" ]
+        symfony-dotenv: [ "^7.0", "^6.0", "^5.0", "^4.0", "^3.3" ]
+        dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
+        include:
+          - php: "8.3"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.2"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.2"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.1"
+            phpunit: "^10.1.0"
+            phpunit-config-file: "phpunit.github-actions.xml.dist"
+          - php: "8.0"
+            phpunit: "^9.3"
+            phpunit-config-file: "phpunit.github-actions.up-to-9.xml.dist"
+          - os: "ubuntu-latest"
+            os-title: "ubuntu"
+          - os: "macos-latest"
+            os-title: "macos"
+          - os: "windows-latest"
+            os-title: "win"
+          - dependency-prefer: "prefer-stable"
+            dependency-prefer-title: "stable"
+          - dependency-prefer: "prefer-lowest"
+            dependency-prefer-title: "lowest"
+        exclude:
+          - php: "8.1"
+            symfony-dotenv: "^7.0"
+          - php: "8.0"
+            symfony-dotenv: "^7.0"
+
+    steps:
+
+      - name: "Checkout code"
+        uses: "actions/checkout@v4"
+
+      - name: "Validate composer.json and composer.lock"
+        run: "composer validate --strict"
+
+      - name: "Setup PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          php-version: "${{ matrix.php }}"
+          extensions: fileinfo, mbstring
+          ini-values: error_reporting=E_ALL
+          coverage: none
+        env:
+          COMPOSER_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+
+      # find composer's cache directory - so we know which directory to cache in the next step
+      - name: "Find composer's cache directory"
+        id: "composer-cache"
+        shell: bash # make sure this step works on Windows - see https://github.com/actions/runner/issues/2224#issuecomment-1289533957
+        run: |
+          echo "composer_cache_dir=$(composer config cache-files-dir)">> "$GITHUB_OUTPUT"
+
+      - name: "Cache composer's cache directory"
+        uses: "actions/cache@v3"
+        with:
+          path: "${{ steps.composer-cache.outputs.composer_cache_dir }}"
+          key: "[${{ matrix.os }}][php-${{ matrix.php }}][symfony/dotenv-${{ matrix.symfony-dotenv }}][${{ matrix.dependency-prefer }}][composer.json-${{ hashFiles('composer.json') }}]"
+
+      - name: "Install dependencies"
+        uses: "nick-fields/retry@v2"
+        with:
+          timeout_minutes: 5
+          max_attempts: 5
+          shell: bash # make sure "^" characters are interpreted properly on Windows (e.g. in "^5.0")
+          command: |
+            composer remove "infection/infection" --dev --no-interaction --no-update
+            composer remove "phpcsstandards/php_codesniffer" --dev --no-interaction --no-update
+            composer remove "phpstan/phpstan" --dev --no-interaction --no-update
+            composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
+            composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" --dev --no-interaction --no-update
+            composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
+
+      - name: "Execute tests"
+        run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
 
 
 
@@ -286,7 +294,7 @@ jobs:
       matrix:
         os: [ "ubuntu-latest", "macos-latest", "windows-latest" ]
         php: [ "7.4", "7.3", "7.2", "7.1", "7.0" ]
-        symfony-dotenv: [ "^6.0", "^5.0", "^4.0", "^3.3" ]
+        symfony-dotenv: [ "^7.0", "^6.0", "^5.0", "^4.0", "^3.3" ]
         dependency-prefer: [ "prefer-stable", "prefer-lowest" ]
         include:
           - php: "7.4"
@@ -315,16 +323,26 @@ jobs:
           - dependency-prefer: "prefer-lowest"
             dependency-prefer-title: "lowest"
         exclude:
+          - php: "7.4"
+            symfony-dotenv: "^7.0"
           - php: "7.4"
             symfony-dotenv: "^6.0"
+          - php: "7.3"
+            symfony-dotenv: "^7.0"
           - php: "7.3"
             symfony-dotenv: "^6.0"
+          - php: "7.2"
+            symfony-dotenv: "^7.0"
           - php: "7.2"
             symfony-dotenv: "^6.0"
+          - php: "7.1"
+            symfony-dotenv: "^7.0"
           - php: "7.1"
             symfony-dotenv: "^6.0"
           - php: "7.1"
             symfony-dotenv: "^5.0"
+          - php: "7.0"
+            symfony-dotenv: "^7.0"
           - php: "7.0"
             symfony-dotenv: "^6.0"
           - php: "7.0"
@@ -368,246 +386,14 @@ jobs:
         with:
           timeout_minutes: 5
           max_attempts: 5
+          shell: bash # make sure "^" characters are interpreted properly on Windows (e.g. in "^5.0")
           command: |
             composer remove "infection/infection" --dev --no-interaction --no-update
+            composer remove "phpcsstandards/php_codesniffer" --dev --no-interaction --no-update
             composer remove "phpstan/phpstan" --dev --no-interaction --no-update
-            composer remove "squizlabs/php_codesniffer" --dev --no-interaction --no-update
             composer require "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
             composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" --dev --no-interaction --no-update
             composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction --optimize-autoloader --no-progress
 
       - name: "Execute tests"
         run: vendor/bin/phpunit "--configuration=${{ matrix.phpunit-config-file }}" --no-coverage --stop-on-error --stop-on-failure
-
-
-
-#  symfony-dotenv-6:
-#
-#    name: PHP ${{ matrix.php }} - symfony/dotenv ${{ matrix.symfony-dotenv }} - ${{ matrix.os }} - ${{ matrix.dependency-prefer }}
-#    runs-on: ${{ matrix.os }}
-#    strategy:
-#      fail-fast: true
-#      matrix:
-#        os: [ubuntu-latest, macos-latest, windows-latest]
-#        php: [8.2, 8.1, "8.0"]
-#        symfony-dotenv: [^6.0]
-#        dependency-prefer: [prefer-stable, prefer-lowest]
-#        phpunit-config-file: ["phpunit.up-to-9.xml.dist"]
-#        include:
-#          - php: 8.2
-#            phpunit: ^9.3
-#          - php: 8.1
-#            phpunit: ^9.3
-#          - php: "8.0"
-#            phpunit: ^9.3
-#
-#    steps:
-#      - name: Checkout code
-#        uses: actions/checkout@v2
-#
-#      - name: Setup PHP
-#        uses: shivammathur/setup-php@v2
-#        with:
-#          php-version: ${{ matrix.php }}
-#          extensions: fileinfo, mbstring
-#          coverage: none
-#
-##      # find out composer's cache directory on the current os - for the "Cache dependencies (composer)" step below
-##      - name: Determine composer's cache directory
-##        id: composer-cache
-##        run: |
-##          echo "::set-output name=dir::$(composer config cache-files-dir)"
-##
-##      - name: Cache dependencies (composer)
-##        uses: actions/cache@v2
-##        with:
-##          path: ${{ steps.composer-cache.outputs.dir }}
-##          key: php-${{ matrix.php }}-symfony-dotenv-${{ matrix.symfony-dotenv }}-os-${{ matrix.os }}-dependency-prefer-${{ matrix.dependency-prefer }}-composer-${{ hashFiles('composer.json') }}
-#
-#      - name: Install dependencies (composer)
-#        run: |
-#          composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#          composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction
-#
-#      - name: Execute tests
-#        run: vendor/bin/phpunit --configuration=${{ matrix.phpunit-config-file }} --no-coverage --stop-on-error --stop-on-failure
-#
-#  symfony-dotenv-5:
-#
-#    name: PHP ${{ matrix.php }} - symfony/dotenv ${{ matrix.symfony-dotenv }} - ${{ matrix.os }} - ${{ matrix.dependency-prefer }}
-#    runs-on: ${{ matrix.os }}
-#    strategy:
-#      fail-fast: true
-#      matrix:
-#        os: [ubuntu-latest, macos-latest, windows-latest]
-#        php: [7.4, 7.3, 7.2]
-#        symfony-dotenv: [^5.0]
-#        dependency-prefer: [prefer-stable, prefer-lowest]
-#        phpunit-config-file: ["phpunit.up-to-9.xml.dist"]
-#        include:
-#          - php: 7.4
-#            phpunit: ^9.0
-#          - php: 7.3
-#            phpunit: ^9.0
-#          - php: 7.2
-#            phpunit: ^8.0
-#
-#    steps:
-#      - name: Checkout code
-#        uses: actions/checkout@v2
-#
-#      - name: Setup PHP
-#        uses: shivammathur/setup-php@v2
-#        with:
-#          php-version: ${{ matrix.php }}
-#          extensions: fileinfo, mbstring
-#          coverage: none
-#
-##      # find out composer's cache directory on the current os - for the "Cache dependencies (composer)" step below
-##      - name: Determine composer's cache directory
-##        id: composer-cache
-##        run: |
-##          echo "::set-output name=dir::$(composer config cache-files-dir)"
-##
-##      - name: Cache dependencies (composer)
-##        uses: actions/cache@v2
-##        with:
-##          path: ${{ steps.composer-cache.outputs.dir }}
-##          key: php-${{ matrix.php }}-symfony-dotenv-${{ matrix.symfony-dotenv }}-os-${{ matrix.os }}-dependency-prefer-${{ matrix.dependency-prefer }}-composer-${{ hashFiles('composer.json') }}
-#
-#      - name: Install dependencies (composer)
-#        run: |
-#          composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#          composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction
-#
-#      - name: Execute tests
-#        run: vendor/bin/phpunit --configuration=${{ matrix.phpunit-config-file }} --no-coverage --stop-on-error --stop-on-failure
-#
-#  symfony-dotenv-4:
-#
-#    name: PHP ${{ matrix.php }} - symfony/dotenv ${{ matrix.symfony-dotenv }} - ${{ matrix.os }} - ${{ matrix.dependency-prefer }}
-#    runs-on: ${{ matrix.os }}
-#    strategy:
-#      fail-fast: true
-#      matrix:
-#        os: [ubuntu-latest, macos-latest, windows-latest]
-#        php: [7.4, 7.3, 7.2, 7.1]
-#        symfony-dotenv: [^4.0]
-#        dependency-prefer: [prefer-stable, prefer-lowest]
-#        phpunit-config-file: ["phpunit.up-to-9.xml.dist"]
-#        include:
-#          - php: 7.4
-#            phpunit: ^9.0
-#          - php: 7.3
-#            phpunit: ^9.0
-#          - php: 7.2
-#            phpunit: ^8.0
-#          - php: 7.1
-#            phpunit: ^7.0
-#
-#    steps:
-#      - name: Checkout code
-#        uses: actions/checkout@v2
-#
-#      - name: Setup PHP
-#        uses: shivammathur/setup-php@v2
-#        with:
-#          php-version: ${{ matrix.php }}
-#          extensions: fileinfo, mbstring
-#          coverage: none
-#
-##      # find out composer's cache directory on the current os - for the "Cache dependencies (composer)" step below
-##      - name: Determine composer's cache directory
-##        id: composer-cache
-##        run: |
-##          echo "::set-output name=dir::$(composer config cache-files-dir)"
-##
-##      - name: Cache dependencies (composer)
-##        uses: actions/cache@v2
-##        with:
-##          path: ${{ steps.composer-cache.outputs.dir }}
-##          key: php-${{ matrix.php }}-symfony-dotenv-${{ matrix.symfony-dotenv }}-os-${{ matrix.os }}-dependency-prefer-${{ matrix.dependency-prefer }}-composer-${{ hashFiles('composer.json') }}
-#
-#      - name: Install dependencies (composer)
-#        run: |
-#          composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#          composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction
-#
-#      - name: Execute tests
-#        run: vendor/bin/phpunit --configuration=${{ matrix.phpunit-config-file }} --no-coverage --stop-on-error --stop-on-failure
-#
-#  symfony-dotenv-33:
-#
-#    name: PHP ${{ matrix.php }} - symfony/dotenv ${{ matrix.symfony-dotenv }} - ${{ matrix.os }} - ${{ matrix.dependency-prefer }}
-#    runs-on: ${{ matrix.os }}
-#    strategy:
-#      fail-fast: true
-#      matrix:
-#        os: [ubuntu-latest, macos-latest, windows-latest]
-#        php: [8.3, 8.2, 8.1, "8.0", 7.4, 7.3, 7.2, 7.1, "7.0"]
-#        symfony-dotenv: [^3.3]
-#        dependency-prefer: [prefer-stable, prefer-lowest]
-#        phpunit-config-file: ["phpunit.xml.dist"]
-#        include:
-#          - php: 8.3
-#            phpunit: "^10.1.0"
-#          - php: 8.2
-#            phpunit: "^10.1.0"
-#          - php: 8.1
-#            phpunit: ^9.3
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: "8.0"
-#            phpunit: ^9.3
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: 7.4
-#            phpunit: "^9.0"
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: 7.3
-#            phpunit: "^9.0"
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: 7.2
-#            phpunit: "^8.0"
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: 7.1
-#            phpunit: "^7.0"
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#          - php: "7.0"
-#            phpunit: "^6.0"
-#            phpunit-config-file: "phpunit.up-to-9.xml.dist"
-#        exclude:
-#          - os: windows-latest
-#            symfony-dotenv: ^3.3 # symfony-dotenv on Windows can't read multiple values with different capitalisations at once (e.g. "On" and "on")
-#          - php: 8.1
-#            dependency-prefer: prefer-lowest
-#            symfony-dotenv: ^3.3 # "Deprecated: preg_match(): Passing null to parameter #4 ($flags) of type int is deprecated" exists in symfony-dotenv before 3.3.14
-#
-#    steps:
-#      - name: Checkout code
-#        uses: actions/checkout@v2
-#
-#      - name: Setup PHP
-#        uses: shivammathur/setup-php@v2
-#        with:
-#          php-version: ${{ matrix.php }}
-#          extensions: fileinfo, mbstring
-#          coverage: none
-#
-##      # find out composer's cache directory on the current os - for the "Cache dependencies (composer)" step below
-##      - name: Determine composer's cache directory
-##        id: composer-cache
-##        run: |
-##          echo "::set-output name=dir::$(composer config cache-files-dir)"
-##
-##      - name: Cache dependencies (composer)
-##        uses: actions/cache@v2
-##        with:
-##          path: ${{ steps.composer-cache.outputs.dir }}
-##          key: php-${{ matrix.php }}-symfony-dotenv-${{ matrix.symfony-dotenv }}-os-${{ matrix.os }}-dependency-prefer-${{ matrix.dependency-prefer }}-composer-${{ hashFiles('composer.json') }}
-#
-#      - name: Install dependencies (composer)
-#        run: |
-#          composer require "symfony/dotenv:${{ matrix.symfony-dotenv }}" "phpunit/phpunit:${{ matrix.phpunit }}" --dev --no-interaction --no-update
-#          composer update --${{ matrix.dependency-prefer }} --prefer-dist --no-interaction
-#
-#      - name: Execute tests
-#        run: vendor/bin/phpunit --configuration=${{ matrix.phpunit-config-file }} --no-coverage --stop-on-error --stop-on-failure
diff --git a/composer.json b/composer.json
index 5621182..0a9865a 100644
--- a/composer.json
+++ b/composer.json
@@ -26,13 +26,14 @@
     "require": {
         "php": "7.0.* | 7.1.* | 7.2.* | 7.3.* | 7.4.* | 8.0.* | 8.1.* | 8.2.* | 8.3.*",
         "ext-mbstring": "*",
-        "vlucas/phpdotenv": "^1.0 | ^2.0 | ^3.0 | ^4.0 | ^5.0"
+        "vlucas/phpdotenv": "^1.1.0 | ^2.0 | ^3.0 | ^4.0 | ^5.0"
     },
     "require-dev": {
+        "infection/infection": "^0.10 | ^0.11 | ^0.12 | ^0.13 | ^0.14 | ^0.15 | ^0.16 | ^0.17 | ^0.18 | ^0.19 | ^0.20 | ^0.21 | ^0.22 | ^0.23 | ^0.24 | ^0.25 | ^0.26 | ^0.27",
         "jchook/phpunit-assert-throws": "^1.0",
+        "phpcsstandards/php_codesniffer": "^3.7.2",
         "phpstan/phpstan": "^0.9 | ^0.10 | ^0.11 | ^0.12 | ^1.0",
-        "phpunit/phpunit": "~4.8 | ^5.0 | ^6.0 | ^7.0 | ^8.0 | ^9.0 | ^10.0",
-        "squizlabs/php_codesniffer": "^3.5"
+        "phpunit/phpunit": "~4.8 | ^5.0 | ^6.0 | ^7.0 | ^8.4 | ^9.0 | ^10.0"
     },
     "autoload": {
         "psr-4": {
@@ -45,14 +46,24 @@
         }
     },
     "scripts": {
-        "test": "vendor/bin/phpunit",
-        "phpstan": "vendor/bin/phpstan analyse -c phpstan.neon --level=max",
-        "phpcs": "vendor/bin/phpcs"
+        "infection": "vendor/bin/infection --threads=max --show-mutations",
+        "phpcbf": "vendor/bin/phpcbf",
+        "phpcs": "vendor/bin/phpcs",
+        "phpstan": "vendor/bin/phpstan.phar analyse --level=max",
+        "test": "vendor/bin/phpunit"
+    },
+    "scripts-descriptions": {
+        "infection": "Run Infection tests",
+        "phpcbf": "Run PHP Code Beautifier and Fixer against your application",
+        "phpcs": "Run PHP CodeSniffer against your application",
+        "phpstan": "Run PHPStan static analysis against your application",
+        "test": "Run PHPUnit tests"
     },
     "config": {
         "sort-packages": true,
         "allow-plugins": {
-            "ocramius/package-versions": true
+            "ocramius/package-versions": true,
+            "infection/extension-installer": true
         }
     }
 }
diff --git a/phpunit.github-actions.up-to-9.xml.dist b/phpunit.github-actions.up-to-9.xml.dist
index 6f1215a..871f7f3 100644
--- a/phpunit.github-actions.up-to-9.xml.dist
+++ b/phpunit.github-actions.up-to-9.xml.dist
@@ -4,7 +4,7 @@
   xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
   backupGlobals="true"
   backupStaticAttributes="true"
-  beStrictAboutOutputDuringTests="true"
+  beStrictAboutOutputDuringTests="false"
   bootstrap="vendor/autoload.php"
   colors="false"
   convertDeprecationsToExceptions="false"
diff --git a/src/DotEnvAdapters/AbstractDotEnvAdapter.php b/src/DotEnvAdapters/AbstractDotEnvAdapter.php
new file mode 100644
index 0000000..4c8e8d7
--- /dev/null
+++ b/src/DotEnvAdapters/AbstractDotEnvAdapter.php
@@ -0,0 +1,214 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters;
+
+use CodeDistortion\FluentDotEnv\Exceptions\GeneralException;
+use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
+use CodeDistortion\FluentDotEnv\Misc\GetenvSupport;
+use CodeDistortion\FluentDotEnv\Misc\ValueStore;
+use Throwable;
+
+/**
+ * Abstract adapter to read .env files.
+ */
+abstract class AbstractDotEnvAdapter implements DotEnvAdapterInterface
+{
+    /** @var array<string, string> The original set of getenv() values. */
+    private $origGetEnv = [];
+
+    /** @var array<string, string> The original set of $_ENV values. */
+    private $origEnv = [];
+
+    /** @var array<string, string> The original set of $_SERVER values. */
+    private $origServer = [];
+
+
+
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    abstract protected function importWillUpdateGetenvValues(): bool;
+
+    /**
+     * When going through the process of backing up and clearing the getenv() values, work out if the code should touch
+     * only the variables defined in the .env file (which requires it to be loaded an extra time beforehand).
+     *
+     * PHP 7.0 and below can't get a list of the current env vars using getenv() (with no arguments).
+     *
+     * So getting the keys from the .env file allows us to override those values and replace them after without needing
+     * to know the full list.
+     *
+     * @return boolean
+     */
+    protected function shouldOnlyWorkWithVariablesDefinedInEnvFile(): bool
+    {
+        // look for PHP 7.0 or below
+        return (bool) version_compare(PHP_VERSION, '7.1.0', '<');
+    }
+
+
+
+    /**
+     * Load the values from the given .env file, and return them.
+     *
+     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
+     *
+     * @param string $path The path to the .env file.
+     * @return ValueStore
+     * @throws InvalidPathException When the directory or file could not be used.
+     * @throws Throwable            Rethrows any other Throwable exception.
+     */
+    public function import(string $path): ValueStore
+    {
+        try {
+
+            $this->recordCurrentEnvValues($path);
+            $this->removeCurrentEnvValues();
+            $valueStore = $this->importValuesFromEnvFile($path);
+
+        } catch (Throwable $e) {
+
+            throw $this->exceptionIsBecauseFileCantBeOpened($e)
+                ? InvalidPathException::invalidPath($path, $e)
+                : $e;
+
+        } finally {
+
+            $valueStore = $valueStore ?? new ValueStore();
+
+            $keysJustOverridden = array_keys($valueStore->all());
+            $this->restoreOriginalEnvValues($keysJustOverridden);
+        }
+
+        return $valueStore;
+    }
+
+
+
+    /**
+     * Record the current environment values, to be restored later.
+     *
+     * @param string $path The path to the .env file.
+     * @return void
+     */
+    private function recordCurrentEnvValues(string $path)
+    {
+        $this->origEnv = $_ENV;
+        $this->origServer = $_SERVER;
+
+        if (!$this->importWillUpdateGetenvValues()) {
+            return;
+        }
+
+        $this->origGetEnv = $this->shouldOnlyWorkWithVariablesDefinedInEnvFile()
+            ? $this->resolveCurrentEnvVarsBasedOnKeysDefinedInEnvFile($path)
+            : GetenvSupport::getAllGetenvVariables();
+    }
+
+    /**
+     * Generate an array of the current env variables, based on the keys defined in the .env file.
+     *
+     * @param string $path The path to the .env file.
+     * @return array<string, string>
+     */
+    private function resolveCurrentEnvVarsBasedOnKeysDefinedInEnvFile(string $path): array
+    {
+        $keys = $this->determineKeysDefinedInEnvFile($path);
+        return GetenvSupport::getParticularGetenvVariables($keys);
+    }
+
+    /**
+     * Look into a dotenv file, and find out which keys it defines.
+     *
+     * @param string $path The path to the .env file.
+     * @return string[]
+     */
+    private function determineKeysDefinedInEnvFile(string $path): array
+    {
+        $envFileValues = $this->parseEnvFileForValues($path);
+
+        return array_keys($envFileValues);
+    }
+
+    /**
+     * Parse the contents of a .env file for key value pairs.
+     *
+     * Used when using PHP 7.0 or below, to determine which keys are in the .env file.
+     *
+     * @param string $path The path to the .env file.
+     * @return array<string, mixed>
+     */
+    protected function parseEnvFileForValues(string $path): array
+    {
+        throw GeneralException::pleaseOverrideMethodInChildClass(static::class, __FUNCTION__);
+    }
+
+
+
+    /**
+     * Remove all current environment values.
+     *
+     * @return void
+     */
+    private function removeCurrentEnvValues()
+    {
+        $_ENV = $_SERVER = [];
+
+        if (!$this->importWillUpdateGetenvValues()) {
+            return;
+        }
+
+        $origGetEnvKeys = array_keys($this->origGetEnv);
+        GetenvSupport::removeGetenvVariables($origGetEnvKeys);
+    }
+
+
+
+    /**
+     * Read the data from the given .env path.
+     *
+     * @param string $path The path to the .env file.
+     * @return ValueStore
+     */
+    abstract protected function importValuesFromEnvFile(string $path): ValueStore;
+
+
+
+    /**
+     * Check if the given exception is because the .env file could not be opened.
+     *
+     * @param Throwable $e The exception to check.
+     * @return boolean
+     */
+    abstract protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool;
+
+
+
+    /**
+     * Restore the original environment values.
+     *
+     * @param string[] $keysJustOverridden The keys that were just overridden.
+     * @return void
+     */
+    private function restoreOriginalEnvValues(array $keysJustOverridden)
+    {
+        $_ENV = $this->origEnv;
+        $_SERVER = $this->origServer;
+
+        if (!$this->importWillUpdateGetenvValues()) {
+            return;
+        }
+
+        // PHP 7.1 and 7.2 on Windows don't pick up keys with empty values
+        // so explicitly remove the values here in case any were empty
+        GetenvSupport::removeGetenvVariables($keysJustOverridden);
+
+        $this->shouldOnlyWorkWithVariablesDefinedInEnvFile()
+            ? GetenvSupport::addGetenvVariables($this->origGetEnv)
+            : GetenvSupport::replaceAllGetenvVariables($this->origGetEnv);
+    }
+}
diff --git a/src/DotEnvAdapters/DotEnvAdapterPicker.php b/src/DotEnvAdapters/DotEnvAdapterPicker.php
index 3823461..1679177 100644
--- a/src/DotEnvAdapters/DotEnvAdapterPicker.php
+++ b/src/DotEnvAdapters/DotEnvAdapterPicker.php
@@ -2,8 +2,7 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters;
 
-use CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony\SymfonyAdapter3;
-use CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony\SymfonyAdapter4Plus;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony\SymfonyAdapter;
 use CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\VLucasAdapterV1;
 use CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\VLucasAdapterV2;
 use CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\VLucasAdapterV3;
@@ -15,7 +14,6 @@
 use Dotenv\Dotenv as DotenvV4;
 use Dotenv\Dotenv as DotenvV5;
 use Dotenv\Environment\DotenvFactory as DotenvFactoryV3;
-use ReflectionMethod;
 use Symfony\Component\Dotenv\Dotenv as SymfonyDotenv;
 
 /**
@@ -56,7 +54,6 @@ public static function pickAdapter(array $order = ['vlucas', 'symfony']): DotEnv
      * Detect the version of vlucas/phpdotenv installed.
      *
      * @return DotEnvAdapterInterface|null
-     * @throws DependencyException When the vlucas/phpdotenv package cannot be found.
      */
     public static function detectVLucasPhpDotEnv()
     {
@@ -78,25 +75,11 @@ public static function detectVLucasPhpDotEnv()
      * Detect the version of symfony/dotenv installed.
      *
      * @return DotEnvAdapterInterface|null
-     * @throws DependencyException When the symfony/dotenv package cannot be found.
      */
     public static function detectSymfonyDotEnv()
     {
-        if (class_exists(SymfonyDotenv::class)) {
-
-            // before version 3.3.7, symfony/dotenv's Dotenv::populate(..) method checked to see if each value is
-            // present in getenv(..) first before importing it. An extra step needs to be taken to compensate for this.
-
-            // to try and detect a change after this so the extra work can be removed, this code looks for the 'void'
-            // return type in the Dotenv::load(..) method which was added in version 4.0.0
-            $reflectionMethod = new ReflectionMethod(SymfonyDotenv::class, 'load');
-            $returnType = $reflectionMethod->getReturnType();
-            $returnTypeName = !is_null($returnType) ? $returnType->getName() : null;
-            if ($returnTypeName == 'void') {
-                return new SymfonyAdapter4Plus();
-            }
-            return new SymfonyAdapter3();
-        }
-        return null;
+        return class_exists(SymfonyDotenv::class)
+            ? new SymfonyAdapter()
+            : null;
     }
 }
diff --git a/src/DotEnvAdapters/DotEnvAdapterTrait.php b/src/DotEnvAdapters/DotEnvAdapterTrait.php
new file mode 100644
index 0000000..997e0d6
--- /dev/null
+++ b/src/DotEnvAdapters/DotEnvAdapterTrait.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters;
+
+use Throwable;
+
+/**
+ * Methods sometimes used by the DotEnv adapters.
+ */
+trait DotEnvAdapterTrait
+{
+    /**
+     * Pick the directory from a path.
+     *
+     * @param string $path The path to the .env file.
+     * @return string
+     */
+    protected function getDir(string $path): string
+    {
+        $temp = explode('/', $path);
+        array_pop($temp); // remove the filename
+        return implode('/', $temp);
+    }
+
+    /**
+     * Pick the filename from a path.
+     *
+     * @param string $path The path to the .env file.
+     * @return string
+     */
+    protected function getFilename(string $path): string
+    {
+        $temp = explode('/', $path);
+        return array_pop($temp);
+    }
+
+    /**
+     * Get the content of a file in the local filesystem.
+     *
+     * Suppresses any errors.
+     *
+     * @param string $path The path to the file.
+     * @return string
+     */
+    private function getFileContent(string $path): string
+    {
+        $content = false;
+        try {
+            $content = @file_get_contents($path);
+        } catch (Throwable $e) {
+        }
+
+        return is_string($content)
+            ? $content
+            : '';
+    }
+}
diff --git a/src/DotEnvAdapters/Symfony/SymfonyAdapter.php b/src/DotEnvAdapters/Symfony/SymfonyAdapter.php
new file mode 100644
index 0000000..e8904b4
--- /dev/null
+++ b/src/DotEnvAdapters/Symfony/SymfonyAdapter.php
@@ -0,0 +1,83 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony;
+
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
+use CodeDistortion\FluentDotEnv\Misc\ValueStore;
+use Symfony\Component\Dotenv\Dotenv;
+use Symfony\Component\Dotenv\Exception\PathException;
+use Throwable;
+
+/**
+ * Adapter for symfony/dotenv.
+ */
+class SymfonyAdapter extends AbstractDotEnvAdapter
+{
+    use DotEnvAdapterTrait;
+
+
+
+    /**
+     * Read the data from the given .env path.
+     *
+     * @param string $path The path to the .env file.
+     * @return ValueStore
+     */
+    protected function importValuesFromEnvFile(string $path): ValueStore
+    {
+        $dotenv = new Dotenv();
+        if (method_exists(Dotenv::class, 'usePutenv')) {
+            $dotenv->usePutenv(false);
+        }
+        $dotenv->load($path);
+
+        unset($_ENV['SYMFONY_DOTENV_VARS']); // symfony/dotenv sets this key
+
+        return new ValueStore($_ENV);
+    }
+
+
+
+    /**
+     * Check if the given exception is because the .env file could not be opened.
+     *
+     * @param Throwable $e The exception to check.
+     * @return boolean
+     */
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
+    {
+        return $e instanceof PathException;
+    }
+
+
+
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // updating of getenv() values will be turned off when this method is available
+        return !method_exists(Dotenv::class, 'usePutenv');
+    }
+
+    /**
+     * Parse the contents of a .env file for key value pairs.
+     *
+     * Used when using PHP 7.0 or below, to determine which keys are in the .env file.
+     *
+     * @param string $path The path to the .env file.
+     * @return array<string, mixed>
+     */
+    protected function parseEnvFileForValues(string $path): array
+    {
+        $content = $this->getFileContent($path);
+
+        // luckily Symfony Dotenv's parse() method is public
+        return (new Dotenv())->parse($content, 'doesnt-matter');
+    }
+}
diff --git a/src/DotEnvAdapters/Symfony/SymfonyAdapter3.php b/src/DotEnvAdapters/Symfony/SymfonyAdapter3.php
deleted file mode 100644
index a24cd8e..0000000
--- a/src/DotEnvAdapters/Symfony/SymfonyAdapter3.php
+++ /dev/null
@@ -1,69 +0,0 @@
-<?php
-
-namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony;
-
-use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterInterface;
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
-use CodeDistortion\FluentDotEnv\Misc\GetenvSupport;
-use CodeDistortion\FluentDotEnv\Misc\ValueStore;
-use Symfony\Component\Dotenv\Dotenv;
-use Throwable;
-use Symfony\Component\Dotenv\Exception\PathException;
-
-/**
- * Adapter for symfony/dotenv.
- */
-class SymfonyAdapter3 implements DotEnvAdapterInterface
-{
-    /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
-     */
-    public function import(string $path): ValueStore
-    {
-        $origGetEnv = GetenvSupport::getenvValues();
-        $origEnv = $_ENV;
-        $origServer = $_SERVER;
-
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
-
-            throw ($e instanceof PathException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
-
-        } finally {
-            GetenvSupport::replaceGetenv($origGetEnv);
-            $_ENV = $origEnv;
-            $_SERVER = $origServer;
-        }
-
-        return $values;
-    }
-
-    /**
-     * Actually import the data from the given .env path
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     */
-    private function runImport(string $path): ValueStore
-    {
-        foreach (GetenvSupport::getenvValues() as $key => $value) {
-            putenv($key);
-        }
-        $_SERVER = $_ENV = [];
-
-        (new Dotenv())->load($path);
-        unset($_SERVER['SYMFONY_DOTENV_VARS']);
-
-        return new ValueStore($_SERVER);
-    }
-}
diff --git a/src/DotEnvAdapters/Symfony/SymfonyAdapter4Plus.php b/src/DotEnvAdapters/Symfony/SymfonyAdapter4Plus.php
deleted file mode 100644
index 5cb66bf..0000000
--- a/src/DotEnvAdapters/Symfony/SymfonyAdapter4Plus.php
+++ /dev/null
@@ -1,62 +0,0 @@
-<?php
-
-namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\Symfony;
-
-use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterInterface;
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
-use CodeDistortion\FluentDotEnv\Misc\ValueStore;
-use Symfony\Component\Dotenv\Dotenv;
-use Throwable;
-use Symfony\Component\Dotenv\Exception\PathException;
-
-/**
- * Adapter for symfony/dotenv.
- */
-class SymfonyAdapter4Plus implements DotEnvAdapterInterface
-{
-    /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
-     */
-    public function import(string $path): ValueStore
-    {
-        $origEnv = $_ENV;
-        $origServer = $_SERVER;
-
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
-
-            throw ($e instanceof PathException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
-
-        } finally {
-            $_ENV = $origEnv;
-            $_SERVER = $origServer;
-        }
-
-        return $values;
-    }
-
-    /**
-     * Actually import the data from the given .env path
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     */
-    private function runImport(string $path): ValueStore
-    {
-        $_SERVER = $_ENV = [];
-
-        (new Dotenv())->load($path);
-        unset($_SERVER['SYMFONY_DOTENV_VARS']);
-        return new ValueStore($_SERVER);
-    }
-}
diff --git a/src/DotEnvAdapters/VLucas/AbstractVLucasAdapter.php b/src/DotEnvAdapters/VLucas/AbstractVLucasAdapter.php
deleted file mode 100644
index 9454240..0000000
--- a/src/DotEnvAdapters/VLucas/AbstractVLucasAdapter.php
+++ /dev/null
@@ -1,25 +0,0 @@
-<?php
-
-namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
-
-use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterInterface;
-
-/**
- * Adapter for vlucas/phpdotenv.
- */
-abstract class AbstractVLucasAdapter implements DotEnvAdapterInterface
-{
-    /**
-     * Split the given path into a directory and filename.
-     *
-     * @param string $path The path to the .env file.
-     * @return string[]
-     */
-    protected function splitPath(string $path): array
-    {
-        $temp = explode('/', $path);
-        $filename = array_pop($temp);
-        $directory = implode('/', $temp);
-        return [(string) $directory, (string) $filename];
-    }
-}
diff --git a/src/DotEnvAdapters/VLucas/Support/VLucasV1Dotenv.php b/src/DotEnvAdapters/VLucas/Support/VLucasV1Dotenv.php
new file mode 100644
index 0000000..973be5b
--- /dev/null
+++ b/src/DotEnvAdapters/VLucas/Support/VLucasV1Dotenv.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\Support;
+
+use Dotenv;
+
+/**
+ * The vlucas/phpdotenv v1 Dotenv class, with an overridden setEnvironmentVariable() method.
+ *
+ * - this is done so it doesn't update $_ENV and getenv() values.
+ */
+class VLucasV1Dotenv extends Dotenv
+{
+    /**
+     * Set a variable.
+     *
+     * Variable set using:
+     * - putenv
+     * - $_ENV
+     * - $_SERVER.
+     *
+     * The environment variable value is stripped of single and double quotes.
+     *
+     * @param string      $name
+     * @param string|null $value
+     *
+     * @return void
+     */
+    public static function setEnvironmentVariable($name, $value = null)
+    {
+        list($name, $value) = static::normaliseEnvironmentVariable($name, $value);
+
+        // Don't overwrite existing environment variables if we're immutable
+        // Ruby's dotenv does this with `ENV[key] ||= value`.
+        if (static::$immutable === true && !is_null(static::findEnvironmentVariable($name))) {
+            return;
+        }
+
+//        putenv("$name=$value");
+//        $_ENV[$name] = $value;
+        $_SERVER[$name] = $value;
+    }
+}
diff --git a/src/DotEnvAdapters/VLucas/Support/VLucasV2Dotenv.php b/src/DotEnvAdapters/VLucas/Support/VLucasV2Dotenv.php
new file mode 100644
index 0000000..965a3e3
--- /dev/null
+++ b/src/DotEnvAdapters/VLucas/Support/VLucasV2Dotenv.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\Support;
+
+use Dotenv\Dotenv;
+
+/**
+ * The vlucas/phpdotenv v2 Dotenv class, updated to use VLucasV2Loader instead of the default Loader.
+ *
+ * - this is done so it doesn't update $_ENV and getenv() values.
+ */
+class VLucasV2Dotenv extends Dotenv
+{
+    /**
+     * Load `.env` file in given directory
+     */
+    public function load()
+    {
+        $this->loader = new VLucasV2Loader($this->filePath, $immutable = true);
+        return $this->loader->load();
+    }
+
+    /**
+     * Load `.env` file in given directory
+     */
+    public function overload()
+    {
+        $this->loader = new VLucasV2Loader($this->filePath, $immutable = false);
+        return $this->loader->load();
+    }
+}
diff --git a/src/DotEnvAdapters/VLucas/Support/VLucasV2Loader.php b/src/DotEnvAdapters/VLucas/Support/VLucasV2Loader.php
new file mode 100644
index 0000000..dd7c574
--- /dev/null
+++ b/src/DotEnvAdapters/VLucas/Support/VLucasV2Loader.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\Support;
+
+use Dotenv\Loader;
+
+/**
+ * The vlucas/phpdotenv v2 Loader class, with an overridden setEnvironmentVariable() method.
+ *
+ * - this is done so it doesn't update $_ENV and getenv() values.
+ */
+class VLucasV2Loader extends Loader
+{
+    /**
+     * Set a variable using:
+     * - putenv
+     * - $_ENV
+     * - $_SERVER
+     *
+     * The environment variable value is stripped of single and double quotes.
+     *
+     * @param $name
+     * @param null $value
+     */
+    public function setEnvironmentVariable($name, $value = null)
+    {
+        list($name, $value) = $this->normaliseEnvironmentVariable($name, $value);
+
+        // Don't overwrite existing environment variables if we're immutable
+        // Ruby's dotenv does this with `ENV[key] ||= value`.
+        if ($this->immutable === true && !is_null($this->getEnvironmentVariable($name))) {
+            return;
+        }
+
+//        putenv("$name=$value");
+//        $_ENV[$name] = $value;
+        $_SERVER[$name] = $value;
+    }
+}
diff --git a/src/DotEnvAdapters/VLucas/VLucasAdapterV1.php b/src/DotEnvAdapters/VLucas/VLucasAdapterV1.php
index b22ca9b..e54a0ff 100644
--- a/src/DotEnvAdapters/VLucas/VLucasAdapterV1.php
+++ b/src/DotEnvAdapters/VLucas/VLucasAdapterV1.php
@@ -2,69 +2,77 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
 
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
-use CodeDistortion\FluentDotEnv\Misc\GetenvSupport;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\Support\VLucasV1Dotenv;
 use CodeDistortion\FluentDotEnv\Misc\ValueStore;
-use Dotenv;
 use InvalidArgumentException;
 use Throwable;
 
 /**
  * Adapter for vlucas/phpdotenv v1.
  */
-class VLucasAdapterV1 extends AbstractVLucasAdapter
+class VLucasAdapterV1 extends AbstractDotEnvAdapter
 {
+    use DotEnvAdapterTrait;
+
+
+
     /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
+     * Read the data from the given .env path.
      *
      * @param string $path The path to the .env file.
      * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
      */
-    public function import(string $path): ValueStore
+    protected function importValuesFromEnvFile(string $path): ValueStore
     {
-        $origGetEnv = GetenvSupport::getenvValues();
-        $origEnv = $_ENV;
-        $origServer = $_SERVER;
-
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
-
-            throw ($e instanceof InvalidArgumentException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
-
-        } finally {
-            GetenvSupport::replaceGetenv($origGetEnv);
-            $_ENV = $origEnv;
-            $_SERVER = $origServer;
+        $directory = $this->getDir($path);
+        $filename = $this->getFilename($path);
+
+        $dotEnv = new VLucasV1Dotenv();
+        if (method_exists($dotEnv, 'makeMutable')) {
+            $dotEnv->makeMutable();
         }
 
-        return $values;
+        $dotEnv->load($directory, $filename);
+
+        return new ValueStore($_SERVER);
     }
 
+
+
     /**
-     * Actually import the data from the given .env path
+     * Check if the given exception is because the .env file could not be opened.
      *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
+     * @param Throwable $e The exception to check.
+     * @return boolean
      */
-    private function runImport(string $path): ValueStore
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
     {
-        $_SERVER = [];
+        return $e instanceof InvalidArgumentException;
+    }
 
-        $dotEnv = (new Dotenv());
-        if (method_exists($dotEnv, 'makeMutable')) {
-            $dotEnv->makeMutable();
-        }
 
-        list($directory, $filename) = $this->splitPath($path);
-        $dotEnv->load($directory, $filename);
 
-        return new ValueStore($_SERVER);
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // custom class VLucasV1Dotenv overrides Dotenv's setEnvironmentVariable() method
+        // to remove the putenv() and $_ENV lines. HOWEVER:
+        // version <= 1.0.6 don't have the setEnvironmentVariable() method
+        // version <= 1.0.9 some issues in overriding setEnvironmentVariable()
+        // version ^1.1.0 is required in composer.json to avoid problems with these old versions
+
+        // otherwise…
+        // not needed because vlucas/phpdotenv v1 is being used in a way where
+        // it doesn't update getenv() values, it only populates $_SERVER
+        // - see use of overloaded VLucasV1Dotenv class above
+        return false;
     }
 }
diff --git a/src/DotEnvAdapters/VLucas/VLucasAdapterV2.php b/src/DotEnvAdapters/VLucas/VLucasAdapterV2.php
index 92e2a17..36baaff 100644
--- a/src/DotEnvAdapters/VLucas/VLucasAdapterV2.php
+++ b/src/DotEnvAdapters/VLucas/VLucasAdapterV2.php
@@ -2,65 +2,65 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
 
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
-use CodeDistortion\FluentDotEnv\Misc\GetenvSupport;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas\Support\VLucasV2Dotenv;
 use CodeDistortion\FluentDotEnv\Misc\ValueStore;
-use Dotenv\Dotenv;
-use Dotenv\Exception\InvalidPathException as DotEnvInvalidPathException;
 use InvalidArgumentException;
 use Throwable;
 
 /**
  * Adapter for vlucas/phpdotenv v2.
  */
-class VLucasAdapterV2 extends AbstractVLucasAdapter
+class VLucasAdapterV2 extends AbstractDotEnvAdapter
 {
+    use DotEnvAdapterTrait;
+
+
+
     /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
+     * Read the data from the given .env path.
      *
      * @param string $path The path to the .env file.
      * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
      */
-    public function import(string $path): ValueStore
+    protected function importValuesFromEnvFile(string $path): ValueStore
     {
-        $origGetEnv = GetenvSupport::getenvValues();
-        $origEnv = $_ENV;
-        $origServer = $_SERVER;
+        $directory = $this->getDir($path);
+        $filename = $this->getFilename($path);
 
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
+        (new VLucasV2Dotenv($directory, $filename))->overload();
 
-            throw (($e instanceof DotEnvInvalidPathException) || ($e instanceof InvalidArgumentException)
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
+        return new ValueStore($_SERVER);
+    }
 
-        } finally {
-            GetenvSupport::replaceGetenv($origGetEnv);
-            $_ENV = $origEnv;
-            $_SERVER = $origServer;
-        }
 
-        return $values;
-    }
 
     /**
-     * Actually import the data from the given .env path
+     * Check if the given exception is because the .env file could not be opened.
      *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
+     * @param Throwable $e The exception to check.
+     * @return boolean
      */
-    private function runImport(string $path): ValueStore
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
     {
-        $_SERVER = [];
+        return $e instanceof InvalidArgumentException;
+    }
 
-        list($directory, $filename) = $this->splitPath($path);
-        (new Dotenv($directory, $filename))->overload();
 
-        return new ValueStore($_SERVER);
+
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // not needed because vlucas/phpdotenv v2 is being used in a way where
+        // it doesn't update getenv() values, it only populates $_SERVER
+        // - see use of overloaded VLucasV2Dotenv class above
+        return false;
     }
 }
diff --git a/src/DotEnvAdapters/VLucas/VLucasAdapterV3.php b/src/DotEnvAdapters/VLucas/VLucasAdapterV3.php
index 7f144c7..5d00e13 100644
--- a/src/DotEnvAdapters/VLucas/VLucasAdapterV3.php
+++ b/src/DotEnvAdapters/VLucas/VLucasAdapterV3.php
@@ -2,7 +2,8 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
 
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
 use CodeDistortion\FluentDotEnv\Misc\ValueStore;
 use Dotenv\Dotenv;
 use Dotenv\Environment\Adapter\ServerConstAdapter;
@@ -13,55 +14,59 @@
 /**
  * Adapter for vlucas/phpdotenv v3.
  */
-class VLucasAdapterV3 extends AbstractVLucasAdapter
+class VLucasAdapterV3 extends AbstractDotEnvAdapter
 {
+    use DotEnvAdapterTrait;
+
+
+
     /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
+     * Read the data from the given .env path.
      *
      * @param string $path The path to the .env file.
      * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
      */
-    public function import(string $path): ValueStore
+    protected function importValuesFromEnvFile(string $path): ValueStore
     {
-        $origServer = $_SERVER;
+        $directory = $this->getDir($path);
+        $filename = $this->getFilename($path);
 
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
+        // ImportAndPopulate determines what was imported based on $_SERVER
+        // and chooses what to update based on that
+        $factory = new DotenvFactory([new ServerConstAdapter()]);
+        $dotenv = Dotenv::create($directory, $filename, $factory);
+        $dotenv->load();
 
-            throw ($e instanceof DotEnvInvalidPathException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
+        return new ValueStore($_SERVER);
+    }
 
-        } finally {
-            $_SERVER = $origServer;
-        }
 
-        return $values;
-    }
 
     /**
-     * Actually import the data from the given .env path
+     * Check if the given exception is because the .env file could not be opened.
      *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
+     * @param Throwable $e The exception to check.
+     * @return boolean
      */
-    private function runImport(string $path): ValueStore
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
     {
-        $_SERVER = [];
+        return $e instanceof DotEnvInvalidPathException;
+    }
 
-        list($directory, $filename) = $this->splitPath($path);
 
-        // ImportAndPopulate determines what was imported based on $_SERVER
-        // and chooses what to update based on that
-        $factory = new DotenvFactory([new ServerConstAdapter()]);
-        $dotenv = Dotenv::create($directory, $filename, $factory);
-        $dotenv->load();
 
-        return new ValueStore($_SERVER);
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // not needed because vlucas/phpdotenv v3 is being used in a way where
+        // it doesn't update getenv() values, it only populates $_SERVER
+        // - see use of ServerConstAdapter() above
+        return false;
     }
 }
diff --git a/src/DotEnvAdapters/VLucas/VLucasAdapterV4.php b/src/DotEnvAdapters/VLucas/VLucasAdapterV4.php
index bff5049..e439262 100644
--- a/src/DotEnvAdapters/VLucas/VLucasAdapterV4.php
+++ b/src/DotEnvAdapters/VLucas/VLucasAdapterV4.php
@@ -2,7 +2,8 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
 
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
 use CodeDistortion\FluentDotEnv\Misc\ValueStore;
 use Dotenv\Dotenv;
 use Dotenv\Exception\InvalidPathException as DotEnvInvalidPathException;
@@ -13,47 +14,22 @@
 /**
  * Adapter for vlucas/phpdotenv v4.
  */
-class VLucasAdapterV4 extends AbstractVLucasAdapter
+class VLucasAdapterV4 extends AbstractDotEnvAdapter
 {
-    /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
-     */
-    public function import(string $path): ValueStore
-    {
-        $origServer = $_SERVER;
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
+    use DotEnvAdapterTrait;
 
-            throw ($e instanceof DotEnvInvalidPathException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
 
-        } finally {
-            $_SERVER = $origServer;
-        }
-
-        return $values;
-    }
 
     /**
-     * Actually import the data from the given .env path
+     * Read the data from the given .env path.
      *
      * @param string $path The path to the .env file.
      * @return ValueStore
      */
-    private function runImport(string $path): ValueStore
+    protected function importValuesFromEnvFile(string $path): ValueStore
     {
-        $_SERVER = [];
-
-        list($directory, $filename) = $this->splitPath($path);
+        $directory = $this->getDir($path);
+        $filename = $this->getFilename($path);
 
         // ImportAndPopulate determines what was imported based on $_SERVER
         // and chooses what to update based on that
@@ -63,4 +39,34 @@ private function runImport(string $path): ValueStore
 
         return new ValueStore($_SERVER);
     }
+
+
+
+    /**
+     * Check if the given exception is because the .env file could not be opened.
+     *
+     * @param Throwable $e The exception to check.
+     * @return boolean
+     */
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
+    {
+        return $e instanceof DotEnvInvalidPathException;
+    }
+
+
+
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // not needed because vlucas/phpdotenv v4 is being used in a way where
+        // it doesn't update getenv() values, it only populates $_SERVER
+        // - see use of ServerConstAdapter() above
+        return false;
+    }
 }
diff --git a/src/DotEnvAdapters/VLucas/VLucasAdapterV5.php b/src/DotEnvAdapters/VLucas/VLucasAdapterV5.php
index 377b651..32014f1 100644
--- a/src/DotEnvAdapters/VLucas/VLucasAdapterV5.php
+++ b/src/DotEnvAdapters/VLucas/VLucasAdapterV5.php
@@ -2,7 +2,8 @@
 
 namespace CodeDistortion\FluentDotEnv\DotEnvAdapters\VLucas;
 
-use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\AbstractDotEnvAdapter;
+use CodeDistortion\FluentDotEnv\DotEnvAdapters\DotEnvAdapterTrait;
 use CodeDistortion\FluentDotEnv\Misc\ValueStore;
 use Dotenv\Dotenv;
 use Dotenv\Exception\InvalidPathException as DotEnvInvalidPathException;
@@ -13,47 +14,22 @@
 /**
  * Adapter for vlucas/phpdotenv v5.
  */
-class VLucasAdapterV5 extends AbstractVLucasAdapter
+class VLucasAdapterV5 extends AbstractDotEnvAdapter
 {
-    /**
-     * Load the values from the given .env file, and return them.
-     *
-     * NOTE: This MUST leave the getenv(), $_ENV, $_SERVER etc values as they were to begin with.
-     *
-     * @param string $path The path to the .env file.
-     * @return ValueStore
-     * @throws InvalidPathException When the directory or file could not be used.
-     * @throws Throwable            Rethrows any Throwable exception.
-     */
-    public function import(string $path): ValueStore
-    {
-        $origServer = $_SERVER;
-        try {
-            $values = $this->runImport($path);
-        } catch (Throwable $e) {
+    use DotEnvAdapterTrait;
 
-            throw ($e instanceof DotEnvInvalidPathException
-                ? InvalidPathException::invalidPath($path, $e)
-                : $e);
 
-        } finally {
-            $_SERVER = $origServer;
-        }
-
-        return $values;
-    }
 
     /**
-     * Actually import the data from the given .env path
+     * Read the data from the given .env path.
      *
      * @param string $path The path to the .env file.
      * @return ValueStore
      */
-    private function runImport(string $path): ValueStore
+    protected function importValuesFromEnvFile(string $path): ValueStore
     {
-        $_SERVER = [];
-
-        list($directory, $filename) = $this->splitPath($path);
+        $directory = $this->getDir($path);
+        $filename = $this->getFilename($path);
 
         // ImportAndPopulate determines what was imported based on $_SERVER
         // and chooses what to update based on that
@@ -65,4 +41,35 @@ private function runImport(string $path): ValueStore
 
         return new ValueStore($_SERVER);
     }
+
+
+
+    /**
+     * Check if the given exception is because the .env file could not be opened.
+     *
+     * @param Throwable $e The exception to check.
+     * @return boolean
+     */
+    protected function exceptionIsBecauseFileCantBeOpened(Throwable $e): bool
+    {
+        return $e instanceof DotEnvInvalidPathException;
+    }
+
+
+
+    /**
+     * Work out if the import process will update the getenv() values.
+     *
+     * If it doesn't, then the process of backing up and clearing the getenv() values can be skipped.
+     *
+     * @return boolean
+     */
+    protected function importWillUpdateGetenvValues(): bool
+    {
+        // not needed because vlucas/phpdotenv v5 is being used in a way where
+        // it doesn't update getenv() values, it only populates $_SERVER
+        // - see use of ServerConstAdapter() above
+        // and it requires PHP 7.1+ anyway (which means that we can get the full list of current getenv() values anyway)
+        return false;
+    }
 }
diff --git a/src/Exceptions/DependencyException.php b/src/Exceptions/DependencyException.php
index b99767c..09c5335 100644
--- a/src/Exceptions/DependencyException.php
+++ b/src/Exceptions/DependencyException.php
@@ -8,7 +8,7 @@
 class DependencyException extends FluentDotEnvException
 {
     /**
-     * A dot-env package  could not be found.
+     * A dot-env package could not be found.
      *
      * @return self
      */
diff --git a/src/Exceptions/GeneralException.php b/src/Exceptions/GeneralException.php
new file mode 100644
index 0000000..61d4fb2
--- /dev/null
+++ b/src/Exceptions/GeneralException.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace CodeDistortion\FluentDotEnv\Exceptions;
+
+/**
+ * Miscellaneous exceptions.
+ */
+class GeneralException extends FluentDotEnvException
+{
+    /**
+     * Throw an exception when a method is called that should have been overridden.
+     *
+     * @param string $class  The class that is missing the method.
+     * @param string $method The method that is missing.
+     * @return self
+     */
+    public static function pleaseOverrideMethodInChildClass(string $class, string $method): self
+    {
+        return new self("Please override the $method() method in class $class.");
+    }
+}
diff --git a/src/Exceptions/InvalidPathException.php b/src/Exceptions/InvalidPathException.php
index fdea002..c3859fb 100644
--- a/src/Exceptions/InvalidPathException.php
+++ b/src/Exceptions/InvalidPathException.php
@@ -2,7 +2,7 @@
 
 namespace CodeDistortion\FluentDotEnv\Exceptions;
 
-use Exception;
+use Throwable;
 
 /**
  * Exception caused when a path or file could not be found.
@@ -13,10 +13,10 @@ class InvalidPathException extends FluentDotEnvException
      * Invalid path.
      *
      * @param string    $path The path to the directory or file.
-     * @param Exception $e    The original exception that vlucas/phpdotenv threw.
+     * @param Throwable $e    The original exception that vlucas/phpdotenv threw.
      * @return self
      */
-    public static function invalidPath(string $path, Exception $e): self
+    public static function invalidPath(string $path, Throwable $e): self
     {
         return new self("Unable to read from the \"$path\" environment file", 0, $e);
     }
diff --git a/src/FluentDotEnv.php b/src/FluentDotEnv.php
index b898064..e541e88 100644
--- a/src/FluentDotEnv.php
+++ b/src/FluentDotEnv.php
@@ -214,7 +214,7 @@ public function useVlucasPhpDotEnv()
      *
      * @param string|string[] $path The path to the .env file.
      * @return static
-     * @throws DependencyException  When a .env loading package cannot be found (eg. vlucas/phpdotenv).
+     * @throws DependencyException  When a .env loading package cannot be found (e.g. vlucas/phpdotenv).
      * @throws InvalidPathException When the .env file could not be loaded.
      * @throws AlreadyLoadedException When .env values have already been loaded.
      */
@@ -230,7 +230,7 @@ public function load($path)
      *
      * @param string|string[] $path The path to the .env file.
      * @return static
-     * @throws DependencyException When a .env loading package cannot be found (eg. vlucas/phpdotenv).
+     * @throws DependencyException When a .env loading package cannot be found (e.g. vlucas/phpdotenv).
      * @throws AlreadyLoadedException When .env values have already been loaded.
      */
     public function safeLoad($path)
@@ -245,7 +245,7 @@ public function safeLoad($path)
      * @param string[] $paths  The .env paths to load.
      * @param boolean  $safely Should the exception be absorbed when a .env file could not be loaded?.
      * @return static
-     * @throws DependencyException    When a .env loading package cannot be found (eg. vlucas/phpdotenv).
+     * @throws DependencyException    When a .env loading package cannot be found (e.g. vlucas/phpdotenv).
      * @throws InvalidPathException   When the .env file could not be loaded.
      * @throws AlreadyLoadedException When .env values have already been loaded.
      */
@@ -527,12 +527,18 @@ private function retrieveValues(array $keys, $castMethod, bool $needsArray)
     {
         $values = [];
         foreach ($keys as $key) {
+
             $value = $this->valueStore->get($key);
+            $value = is_string($value)
+                ? $value
+                : '';
+
             $values[$key] = ($castMethod
                 ? $this->$castMethod($value)
                 : $value
             );
         }
+
         return ($needsArray ? $values : reset($values));
     }
 
diff --git a/src/Misc/GetenvSupport.php b/src/Misc/GetenvSupport.php
index 91d975f..4aa8b89 100644
--- a/src/Misc/GetenvSupport.php
+++ b/src/Misc/GetenvSupport.php
@@ -12,54 +12,111 @@ class GetenvSupport
     /**
      * Get the full list of current getenv() values.
      *
-     * @return mixed[]
+     * @return array<string, string>
      */
-    public static function getenvValues(): array
+    public static function getAllGetenvVariables(): array
     {
         if ((!function_exists('getenv')) || (!function_exists('putenv'))) {
             return [];
         }
 
-        // getenv requires a $key to be passed to it before PHP 7.1
+        // getenv() requires a $key to be passed to it before PHP 7.1
         try {
-            return (array) getenv();
+
+            return @(array) getenv();
+
         } catch (Throwable $e) {
+
+            // if needed, get the getenv() values individually
+            $values = [];
+            foreach (array_keys($_ENV) as $key) {
+                $values[$key] = getenv($key);
+            }
+            return $values;
+        }
+    }
+
+    /**
+     * Get the current getenv() values for the given keys.
+     *
+     * @param string[] $keys The keys to return values for.
+     * @return array<string, string>
+     */
+    public static function getParticularGetenvVariables(array $keys): array
+    {
+        if ((!function_exists('getenv')) || (!function_exists('putenv'))) {
+            return [];
         }
 
-        // if needed, get the getenv() values individually
         $values = [];
-        foreach (array_keys($_ENV) as $key) {
-            $values[$key] = getenv($key);
+        foreach ($keys as $key) {
+            $value = getenv($key);
+            if ($value !== false) {
+                $values[$key] = $value;
+            }
         }
         return $values;
     }
 
     /**
-     * Set getenv() to contain the given values.
+     * Remove particular getenv() values.
+     *
+     * @param string[] $keys The keys to remove.
+     * @return void
+     */
+    public static function removeGetenvVariables(array $keys)
+    {
+        foreach ($keys as $key) {
+            putenv($key); // clear existing
+        }
+    }
+
+    /**
+     * Set new getenv() values.
+     *
+     * @param array<string, string> $values The values to add to getenv().
+     * @return void
+     */
+    public static function addGetenvVariables(array $values)
+    {
+        foreach ($values as $key => $value) {
+            putenv("$key=$value");
+        }
+    }
+
+    /**
+     * Set getenv() to contain the given values. This replaces the current set of values.
      *
-     * @param string[] $values The values to replace getenv() values with.
+     * @param array<string, string> $newValues The values to replace getenv() values with.
      * @return void
      */
-    public static function replaceGetenv(array $values)
+    public static function replaceAllGetenvVariables(array $newValues)
     {
         if ((!function_exists('getenv')) || (!function_exists('putenv'))) {
             return;
         }
 
-        $currentValues = static::getenvValues();
-        $allValues = array_merge($currentValues, $values);
+        $currentValues = self::getAllGetenvVariables();
 
-        foreach (array_keys($allValues) as $key) {
+        $allKeys = array_unique(
+            array_merge(
+                array_keys($currentValues),
+                array_keys($newValues)
+            )
+        );
+
+        foreach ($allKeys as $key) {
 
             // add or keep
-            if (array_key_exists($key, $values)) {
+            if (array_key_exists($key, $newValues)) {
 
                 // update if different
-                $value = $values[$key];
-                if ((!isset($currentValues[$key])) || ($currentValues[$key] != $value)) {
+                $value = $newValues[$key];
+                if ((!isset($currentValues[$key])) || ($currentValues[$key] !== $value)) {
                     putenv("$key=$value");
                 }
             } else {
+
                 // remove
                 putenv((string) $key);
             }
diff --git a/src/Misc/ValueStore.php b/src/Misc/ValueStore.php
index 8a15275..ee96f47 100644
--- a/src/Misc/ValueStore.php
+++ b/src/Misc/ValueStore.php
@@ -10,14 +10,14 @@ class ValueStore
     /**
      * The imported values.
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $values;
 
     /**
      * The imported values - before any filtering.
      *
-     * @var mixed[]
+     * @var array<string, mixed>
      */
     private $original;
 
@@ -32,7 +32,7 @@ class ValueStore
     /**
      * Constructor.
      *
-     * @param mixed[] $values The imported values.
+     * @param array<string, mixed> $values The imported values.
      */
     public function __construct(array $values = [])
     {
@@ -48,6 +48,7 @@ public function __construct(array $values = [])
     public function merge(ValueStore $valueStore)
     {
         foreach (func_get_args() as $valueStore) {
+            /** @var ValueStore $valueStore */
             $this->original = array_merge(
                 $this->original,
                 $valueStore->original
@@ -92,7 +93,7 @@ public function recalculateValues()
     /**
      * Return all of the stored values.
      *
-     * @return mixed[]
+     * @return array<string, mixed>
      */
     public function all()
     {
diff --git a/src/PipelineActions/Populate/PopulateGetenvAction.php b/src/PipelineActions/Populate/PopulateGetenvAction.php
index a7aac9e..a5fd23b 100644
--- a/src/PipelineActions/Populate/PopulateGetenvAction.php
+++ b/src/PipelineActions/Populate/PopulateGetenvAction.php
@@ -20,7 +20,7 @@ class PopulateGetenvAction extends AbstractPopulationAction
      */
     protected function applyFromValueStore(ValueStore $values)
     {
-        $getenvValues = GetenvSupport::getenvValues();
+        $getenvValues = GetenvSupport::getAllGetenvVariables();
 
         foreach ($values->all() as $key => $value) {
             if (($this->overrideExisting) || (!array_key_exists($key, $getenvValues))) {
@@ -28,7 +28,7 @@ protected function applyFromValueStore(ValueStore $values)
             }
         }
 
-        GetenvSupport::replaceGetenv($getenvValues);
+        GetenvSupport::replaceAllGetenvVariables($getenvValues);
 
         return $this;
     }
diff --git a/tests/Unit/FluentDotEnvTest.php b/tests/Unit/FluentDotEnvTest.php
index ca96a0f..17611cb 100644
--- a/tests/Unit/FluentDotEnvTest.php
+++ b/tests/Unit/FluentDotEnvTest.php
@@ -5,8 +5,8 @@
 use CodeDistortion\FluentDotEnv\Exceptions\AlreadyLoadedException;
 use CodeDistortion\FluentDotEnv\Exceptions\InvalidPathException;
 use CodeDistortion\FluentDotEnv\Exceptions\ValidationException;
-use CodeDistortion\FluentDotEnv\Tests\PHPUnitTestCase;
 use CodeDistortion\FluentDotEnv\FluentDotEnv;
+use CodeDistortion\FluentDotEnv\Tests\PHPUnitTestCase;
 
 /**
  * Test the ConfigDTO class
@@ -30,10 +30,10 @@ protected function customSetUp()
         ];
         putenv('UNTOUCHED_KEY=untouched-value');
         putenv('INITIAL_KEY=initial-value');
-        putenv('NEW_KEY');
-        putenv('EMPTY_KEY');
-        putenv('INTEGER_KEY');
-        putenv('BOOLEAN_KEY');
+        putenv('NEW_KEY'); // i.e. remove
+        putenv('EMPTY_KEY'); // i.e. remove
+        putenv('INTEGER_KEY'); // i.e. remove
+        putenv('BOOLEAN_KEY'); // i.e. remove
     }
 
     /**
@@ -42,7 +42,7 @@ protected function customSetUp()
      *
      * @return FluentDotEnv
      */
-    protected function newFluentDotEnv()
+    protected static function newFluentDotEnv()
     {
         $fDotEnv = FluentDotEnv::new();
         if (file_exists(__DIR__ . '/../../vendor/symfony/dotenv')) {
@@ -56,7 +56,7 @@ protected function newFluentDotEnv()
      *
      * @return array[]
      */
-    public static function CanImportProperlyDataProvider()
+    public static function CanImportProperlyDataProvider(): array
     {
         $notImported = [
             'UNTOUCHED_KEY' => 'untouched-value',
@@ -383,6 +383,7 @@ public static function CanImportProperlyDataProvider()
         foreach ($combinations as $index => $combination) {
             $combinations[$index] = array_merge($default, $combination);
         }
+$combinations = ['filename 2' => $combinations['filename 2']];
         return $combinations;
     }
 
@@ -442,9 +443,10 @@ public function can_import_properly(
         array $expectedServer,
         string $expectedException = null
     ) {
+
         $this->customSetUp();
 
-        $fDotEnv = $this->newFluentDotEnv();
+        $fDotEnv = self::newFluentDotEnv();
 
         // pre-import actions
         if (!is_null($pick)) {
@@ -507,15 +509,15 @@ public function can_import_properly(
                 $expectedException,
                 function () use (&$fDotEnv, $useSafeLoad, $envFilename) {
 
-                    ($useSafeLoad
+                    $useSafeLoad
                         ? $fDotEnv->safeLoad(__DIR__ . '/input/' . $envFilename)
-                        : $fDotEnv->load(__DIR__ . '/input/' . $envFilename));
+                        : $fDotEnv->load(__DIR__ . '/input/' . $envFilename);
                 }
             );
         } else {
-            $values = ($useSafeLoad
+            $values = $useSafeLoad
                 ? $fDotEnv->safeLoad(__DIR__ . '/input/' . $envFilename)->all()
-                : $fDotEnv->load(__DIR__ . '/input/' . $envFilename)->all());
+                : $fDotEnv->load(__DIR__ . '/input/' . $envFilename)->all();
 
             $this->assertSame($expectedValues, $values);
 //            foreach ($expectedGetenv as $key => $value) {
@@ -531,7 +533,7 @@ function () use (&$fDotEnv, $useSafeLoad, $envFilename) {
      *
      * @return array[]
      */
-    public static function CanCallMethodsInDifferentWaysDataProvider()
+    public static function CanCallMethodsInDifferentWaysDataProvider(): array
     {
         $imported = [
             'INITIAL_KEY' => 'override-value',
@@ -905,7 +907,7 @@ public function can_call_methods_in_different_ways(
     ) {
         $this->customSetUp();
 
-        $fDotEnv = $this->newFluentDotEnv();
+        $fDotEnv = self::newFluentDotEnv();
 
         foreach ($methodsAndParams as $oneMethodAndParams) {
             $method = $oneMethodAndParams['method'];
@@ -932,7 +934,7 @@ function () use (&$fDotEnv) {
      *
      * @return array[]
      */
-    public static function canCallValidationAfterLoadDataProvider()
+    public static function canCallValidationAfterLoadDataProvider(): array
     {
         $validCallback = function (string $key, $value) {
             return true;
@@ -1095,17 +1097,21 @@ public function can_call_validation_after_load(
     ) {
 
         $this->customSetUp();
-        $fDotEnv = $this->newFluentDotEnv()->load(__DIR__ . '/input/.env');
+        $fDotEnv = self::newFluentDotEnv()->load(__DIR__ . '/input/.env');
+        $callable = [$fDotEnv, $method];
+        if (!is_callable($callable)) {
+            self::fail();
+        }
 
         if ($expectedException) {
             $this->assertThrows(
                 $expectedException,
-                function () use (&$fDotEnv, $method, $params) {
-                    call_user_func_array([$fDotEnv, $method], $params);
+                function () use ($callable, $params) {
+                    call_user_func_array($callable, $params);
                 }
             );
         } else {
-            call_user_func_array([$fDotEnv, $method], $params);
+            call_user_func_array($callable, $params);
             $this->assertTrue(true);
         }
 
@@ -1122,7 +1128,7 @@ public function pick_after_load_works()
     {
         $this->customSetUp();
 
-        $fDotEnv = $this->newFluentDotEnv()->load(__DIR__ . '/input/.env')->pick('NEW_KEY')->pick('EMPTY_KEY');
+        $fDotEnv = self::newFluentDotEnv()->load(__DIR__ . '/input/.env')->pick('NEW_KEY')->pick('EMPTY_KEY');
         $this->assertSame(
             [
                 'NEW_KEY' => 'new-value1',
@@ -1131,7 +1137,7 @@ public function pick_after_load_works()
             $fDotEnv->all()
         );
 
-        $fDotEnv = $this->newFluentDotEnv()->load(__DIR__ . '/input/.env');
+        $fDotEnv = self::newFluentDotEnv()->load(__DIR__ . '/input/.env');
         $this->assertSame(
             [
                 'INITIAL_KEY' => 'override-value',
@@ -1155,28 +1161,28 @@ public function loading_multiple_env_files_works()
         $this->customSetUp();
 
         // passed in an array
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load([__DIR__ . '/input/1.env']);
         $this->assertSame(['MY_VALUE1' => 'a'], $fDotEnv->all());
 
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load([__DIR__ . '/input/1.env', __DIR__ . '/input/2.env']);
         $this->assertSame(['MY_VALUE1' => 'b'], $fDotEnv->all());
 
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load([__DIR__ . '/input/2.env', __DIR__ . '/input/1.env']);
         $this->assertSame(['MY_VALUE1' => 'a'], $fDotEnv->all());
 
         // passed as separate parameters
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load(__DIR__ . '/input/1.env');
         $this->assertSame(['MY_VALUE1' => 'a'], $fDotEnv->all());
 
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load(__DIR__ . '/input/1.env', __DIR__ . '/input/2.env');
         $this->assertSame(['MY_VALUE1' => 'b'], $fDotEnv->all());
 
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->load(__DIR__ . '/input/2.env', __DIR__ . '/input/1.env');
         $this->assertSame(['MY_VALUE1' => 'a'], $fDotEnv->all());
 
@@ -1184,7 +1190,7 @@ public function loading_multiple_env_files_works()
         $this->assertThrows(
             AlreadyLoadedException::class,
             function () {
-                $this->newFluentDotEnv()
+                self::newFluentDotEnv()
                     ->load(__DIR__ . '/input/1.env')
                     ->load(__DIR__ . '/input/2.env');
             }
@@ -1193,7 +1199,7 @@ function () {
         $this->assertThrows(
             AlreadyLoadedException::class,
             function () {
-                $this->newFluentDotEnv()
+                self::newFluentDotEnv()
                     ->safeLoad(__DIR__ . '/input/1.env')
                     ->safeLoad(__DIR__ . '/input/2.env');
             }
@@ -1203,24 +1209,24 @@ function () {
         $this->assertThrows(
             InvalidPathException::class,
             function () {
-                $this->newFluentDotEnv()
+                self::newFluentDotEnv()
                     ->load([__DIR__ . '/input/missing.env']);
             }
         );
         $this->assertThrows(
             InvalidPathException::class,
             function () {
-                $this->newFluentDotEnv()
+                self::newFluentDotEnv()
                     ->load([__DIR__ . '/input/1.env', __DIR__ . '/input/missing.env', __DIR__ . '/input/2.env']);
             }
         );
 
         // missing file - but with safeLoad()
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->safeLoad(__DIR__ . '/input/missing.env');
         $this->assertSame([], $fDotEnv->all());
 
-        $fDotEnv = $this->newFluentDotEnv()
+        $fDotEnv = self::newFluentDotEnv()
             ->safeLoad(__DIR__ . '/input/1.env', __DIR__ . '/input/missing.env', __DIR__ . '/input/2.env');
         $this->assertSame(['MY_VALUE1' => 'b'], $fDotEnv->all());
     }
@@ -1230,8 +1236,37 @@ function () {
      *
      * @return array[]
      */
-    public static function canCastProperlyDataProvider()
+    public static function canCastProperlyDataProvider(): array
     {
+        // symfony/dotenv ^3.3 on Windows does not support uppercase values
+        // perform an initial test to work out if such values should be excluded from the test
+        $fDotEnv = self::newFluentDotEnv()->safeLoad(__DIR__ . '/input/cast.env');
+        $supportsUppercaseValues = $fDotEnv->get('TrUe') === 'TrUe';
+
+        $keysWithUppercaseValues = [
+            'TrUe',
+            'TRUE',
+            'FaLsE',
+            'FALSE',
+            'On',
+            'ON',
+            'Off',
+            'OFF',
+            'YeS',
+            'YES',
+            'No',
+            'NO',
+        ];
+        $hasUpperCaseChar = function ($value) use ($keysWithUppercaseValues): bool {
+            return in_array($value, $keysWithUppercaseValues, true);
+        };
+
+        $includeKey = function ($value) use ($supportsUppercaseValues, $hasUpperCaseChar): bool {
+            return $supportsUppercaseValues || !$hasUpperCaseChar($value);
+        };
+
+
+
         $boolean = [
             'true' => true,
             'TrUe' => true,
@@ -1267,6 +1302,11 @@ public static function canCastProperlyDataProvider()
         $return = [];
         foreach (['castBoolean' => $boolean, 'castInteger' => $integer] as $castMethod => $tests) {
             foreach ($tests as $key => $expected) {
+
+                if (!$includeKey($key)) {
+                    continue;
+                }
+
                 $return[] = [
                     'castMethod' => $castMethod,
                     'key' => (string) $key,
@@ -1290,7 +1330,7 @@ public static function canCastProperlyDataProvider()
      */
     public function can_cast_properly(string $castMethod, string $key, $expected)
     {
-        $fDotEnv = $this->newFluentDotEnv()->safeLoad(__DIR__ . '/input/cast.env');
+        $fDotEnv = self::newFluentDotEnv()->safeLoad(__DIR__ . '/input/cast.env');
         $this->assertSame($expected, $fDotEnv->$castMethod($key));
     }
 
@@ -1299,7 +1339,7 @@ public function can_cast_properly(string $castMethod, string $key, $expected)
      *
      * @return array[]
      */
-    public static function canGetMultipleValuesDataProvider()
+    public static function canGetMultipleValuesDataProvider(): array
     {
         return [
             // GET
@@ -1473,7 +1513,7 @@ public static function canGetMultipleValuesDataProvider()
      */
     public function can_get_multiple_values(string $method, array $params, $expected)
     {
-        $fDotEnv = $this->newFluentDotEnv()->safeLoad(__DIR__ . '/input/many_values.env');
+        $fDotEnv = self::newFluentDotEnv()->safeLoad(__DIR__ . '/input/many_values.env');
 
         $callable = [$fDotEnv, $method];
         if (is_callable($callable)) {
@@ -1481,4 +1521,37 @@ public function can_get_multiple_values(string $method, array $params, $expected
             $this->assertSame($expected, $output);
         }
     }
+
+    /**
+     * Test that the ->load() doesn't change the existing getenv(), $_SERVER and $_ENV values.
+     *
+     * @test
+     * @return void
+     */
+    public function current_env_values_arent_changed_by_loading_process()
+    {
+        $this->customSetUp();
+
+        $fDotEnv = self::newFluentDotEnv()->load(__DIR__ . '/input/.env');
+
+        // the loaded .env values
+        $this->assertSame('', $fDotEnv->get('UNTOUCHED_KEY'));
+        $this->assertSame('override-value', $fDotEnv->get('INITIAL_KEY'));
+        $this->assertSame('new-value1', $fDotEnv->get('NEW_KEY'));
+
+        // the getenv() values
+        $this->assertSame('untouched-value', getenv('UNTOUCHED_KEY'));
+        $this->assertSame('initial-value', getenv('INITIAL_KEY'));
+        $this->assertFalse(getenv('NEW_KEY'));
+
+        // the $_SERVER values
+        $this->assertSame('untouched-value', $_SERVER['UNTOUCHED_KEY']);
+        $this->assertSame('initial-value', $_SERVER['INITIAL_KEY']);
+        $this->assertFalse(array_key_exists('NEW_KEY', $_SERVER));
+
+        // the $_ENV values
+        $this->assertSame('untouched-value', $_ENV['UNTOUCHED_KEY']);
+        $this->assertSame('initial-value', $_ENV['INITIAL_KEY']);
+        $this->assertFalse(array_key_exists('NEW_KEY', $_ENV));
+    }
 }