diff --git a/.travis.yml b/.travis.yml
index a22d24e..44589ab 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,11 @@
 language: php
 
+dist: bionic
+
 php:
     - 7.4
     - 8.0
-    - nightly
+    - 8.1.0
 
 matrix:
     allow_failures:
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 280e637..bc8b8cc 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -22,7 +22,7 @@ These are run offline at the developers request. The purpose of these tests is t
 
 > Update details accordingly
 
-`tests/create-test-db.sh`
+`tests/Integration/create-test-db.sh`
 
 ### Running the tests
 
diff --git a/composer.json b/composer.json
index 4fcb513..5d802dc 100644
--- a/composer.json
+++ b/composer.json
@@ -14,14 +14,14 @@
         }
     },
     "require": {
-        "php": "^7.4 || ^8.0",
+        "php": "^7.4 || ^8.0 || ^8.1",
         "cache/array-adapter": "^1.1",
         "doctrine/annotations": "^1.13"
     },
     "require-dev": {
         "phpunit/phpunit": "^7 || ^9",
         "roots/wordpress": "^5.8",
-        "symfony/dotenv": "^5.3",
+        "symfony/dotenv": "^5.3 || ^6.0",
         "wp-phpunit/wp-phpunit": "^5.8",
         "yoast/phpunit-polyfills": "^1.0"
     },
@@ -38,7 +38,8 @@
         "test:coverage": "php -dxdebug.mode=coverage bin/phpunit --coverage-clover='./clover.xml'",
         "test:integration": "vendor/bin/phpunit --testsuite integration",
         "php-cs-fixer:test": "tools/php-cs-fixer/vendor/bin/php-cs-fixer fix -v --diff --dry-run",
-        "php-cs-fixer:fix": "tools/php-cs-fixer/vendor/bin/php-cs-fixer fix -v --diff"
+        "php-cs-fixer:fix": "tools/php-cs-fixer/vendor/bin/php-cs-fixer fix -v --diff",
+        "install-tools": "@composer install --working-dir=tools/php-cs-fixer"
     },
     "extra": {
         "wordpress-install-dir": "tests/integration/wp"
diff --git a/tests/Integration/HooksIntegrationTest.php b/tests/Integration/HooksIntegrationTest.php
index abf5783..0cf21c2 100644
--- a/tests/Integration/HooksIntegrationTest.php
+++ b/tests/Integration/HooksIntegrationTest.php
@@ -2,14 +2,17 @@
 
 declare(strict_types=1);
 
+namespace BoxUk\WpHookAttributes\Tests\Integration;
+
 use BoxUk\WpHookAttributes\WordPressHookAttributes;
+use WP_UnitTestCase;
 
 /**
  * @group integration
  */
 class HooksIntegrationTest extends WP_UnitTestCase
 {
-    public function setUp()
+    public function setUp(): void
     {
         // Makes the tests much faster.
         tests_add_filter('wp_hook_attributes_registered_namespaces', function () {
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 3007218..f6141d3 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -15,7 +15,8 @@
 
 if ($is_integration) {
     if (is_readable(__DIR__ . '/integration/.env')) {
-        $dotenv = new Dotenv(true);
+        $dotenv = new Dotenv();
+        $dotenv->usePutenv(true);
         $dotenv->load(__DIR__ . '/integration/.env');
     }