diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 02423916..243d7c12 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -10,7 +10,6 @@ jobs:
   test:
     runs-on: ${{ matrix.os }}
     strategy:
-      max-parallel: 4
       fail-fast: false
       matrix:
         os: [ ubuntu-18.04, ubuntu-latest, windows-latest, macos-latest ]
@@ -26,7 +25,15 @@ jobs:
         bundler-cache: true
         ruby-version: ${{ matrix.ruby-version }}
 
-    - run: bundle exec rake --trace || cat /tmp/1/configure.log
+# https://github.com/microsoft/vcpkg/issues/15931
+# no good solution :(
+    - name: Workaround for vcpkg
+      if: startsWith(matrix.os, 'ubuntu')
+      run: | 
+        sudo apt-get update
+        sudo apt-get install gperf
+
+    - run: bundle exec rake
 
   build:
     runs-on: ${{ matrix.os }}
@@ -50,26 +57,34 @@ jobs:
             platform: x86_64-darwin
             ruby-version: '2.7'
     steps:
-      - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
 
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby-version }}
-          bundler-cache: true
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: true
 
-      - run: bundle exec rake gem:native:${{ matrix.platform }} --trace
+# https://github.com/microsoft/vcpkg/issues/15931
+# no good solution :(
+    - name: Workaround for vcpkg
+      if: startsWith(matrix.os, 'ubuntu')
+      run: | 
+        sudo apt-get update
+        sudo apt-get install gperf
 
-      - uses: actions/upload-artifact@v2
-        with:
-          name: pkg
-          path: pkg/*.gem
+    - run: bundle exec rake gem:native:${{ matrix.platform }}
 
-      - name: Install gem
-        run: gem install -b pkg/emf2svg-*.gem
+    - uses: actions/upload-artifact@v2
+      with:
+        name: pkg
+        path: pkg/*.gem
+
+    - name: Install gem
+      run: gem install -b pkg/emf2svg-*.gem
 
-      - name: Test conversion
-        run: |
-          ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
+    - name: Test conversion
+      run: |
+        ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
 
   test-build:
     needs: build
@@ -104,27 +119,36 @@ jobs:
             ruby-version: '2.7'
             
     steps:
-      - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
+
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
 
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby-version }}
+    - uses: actions/download-artifact@v2
+      with:
+        name: pkg
+        path: pkg
 
-      - uses: actions/download-artifact@v2
-        with:
-          name: pkg
-          path: pkg
+# https://github.com/microsoft/vcpkg/issues/15931
+# no good solution :(
+    - name: Workaround for vcpkg
+      if: startsWith(matrix.os, 'ubuntu')
+      run: | 
+        sudo apt-get update
+        sudo apt-get install gperf
 
-      - name: Install native gem
-        if: matrix.platform == 'any'
-        run: gem install -b pkg/emf2svg-$(ruby -I lib -r emf2svg/version -e "puts Emf2svg::VERSION").gem
+    - name: Install native gem
+      if: matrix.platform == 'any'
+      run: gem install -b pkg/emf2svg-$(ruby -I lib -r emf2svg/version -e "puts Emf2svg::VERSION").gem
 
-      - name: Install binary gem
-        if: matrix.platform != 'any'
-        run: gem install -b pkg/emf2svg-*-${{ matrix.platform }}.gem
-      - name: Test conversion
-        run: |
-          ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
+    - name: Install binary gem
+      if: matrix.platform != 'any'
+      run: gem install -b pkg/emf2svg-*-${{ matrix.platform }}.gem
+
+    - name: Test conversion
+      run: |
+        ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
 
   cross:
     runs-on: ${{ matrix.os }}
@@ -138,25 +162,25 @@ jobs:
             platform: arm64-darwin
             ruby-version: '2.7'
     steps:
-      - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
 
-      - name: Install packages
-        if: matrix.os == 'ubuntu-latest'
-        run: |
-          sudo apt-get update
-          sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu gperf
+    - name: Install packages
+      if: matrix.os == 'ubuntu-latest'
+      run: |
+        sudo apt-get update
+        sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu gperf
         
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby-version }}
-          bundler-cache: true
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: true
 
-      - run: bundle exec rake gem:native:${{ matrix.platform }}
+    - run: bundle exec rake gem:native:${{ matrix.platform }}
 
-      - uses: actions/upload-artifact@v2
-        with:
-          name: pkg
-          path: pkg/*.gem
+    - uses: actions/upload-artifact@v2
+      with:
+        name: pkg
+        path: pkg/*.gem
 
-      - name: Install gem
-        run: gem install -b pkg/emf2svg-*.gem
+    - name: Install gem
+      run: gem install -b pkg/emf2svg-*.gem
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5d98663f..bff2b19c 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -29,26 +29,34 @@ jobs:
             platform: x86_64-darwin
             ruby-version: '2.7'
     steps:
-      - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
 
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby-version }}
-          bundler-cache: true
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: true
 
-      - run: bundle exec rake gem:native:${{ matrix.platform }}
+# https://github.com/microsoft/vcpkg/issues/15931
+# no good solution :(
+    - name: Workaround for vcpkg
+      if: startsWith(matrix.os, 'ubuntu')
+      run: | 
+        sudo apt-get update
+        sudo apt-get install gperf
 
-      - uses: actions/upload-artifact@v2
-        with:
-          name: pkg
-          path: pkg/*.gem
+    - run: bundle exec rake gem:native:${{ matrix.platform }}
 
-      - name: Install gem
-        run: gem install -b pkg/emf2svg-*.gem
+    - uses: actions/upload-artifact@v2
+      with:
+        name: pkg
+        path: pkg/*.gem
 
-      - name: Test conversion
-        run: |
-          ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
+    - name: Install gem
+      run: gem install -b pkg/emf2svg-*.gem
+
+    - name: Test conversion
+      run: |
+        ruby -remf2svg -e "puts File.write('output.svg', Emf2svg.from_file('spec/examples/image1.emf'), mode: 'wb')"
 
   cross:
     runs-on: ${{ matrix.os }}
@@ -64,56 +72,56 @@ jobs:
             platform: arm64-darwin
             ruby-version: '2.7'
     steps:
-      - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
 
-      - name: Install packages
-        if: matrix.os == 'ubuntu-latest'
-        run: |
-          sudo apt-get update
-          sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu gperf
+    - name: Install packages
+      if: matrix.os == 'ubuntu-latest'
+      run: |
+        sudo apt-get update
+        sudo apt-get install gcc-aarch64-linux-gnu g++-aarch64-linux-gnu binutils-aarch64-linux-gnu gperf
         
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: ${{ matrix.ruby-version }}
-          bundler-cache: true
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: true
 
-      - run: bundle exec rake gem:native:${{ matrix.platform }}
+    - run: bundle exec rake gem:native:${{ matrix.platform }}
 
-      - uses: actions/upload-artifact@v2
-        with:
-          name: pkg
-          path: pkg/*.gem
+    - uses: actions/upload-artifact@v2
+      with:
+        name: pkg
+        path: pkg/*.gem
 
-      - name: Install gem
-        run: gem install -b pkg/emf2svg-*.gem
+    - name: Install gem
+      run: gem install -b pkg/emf2svg-*.gem
 
   publish:
     needs: [ build, cross ]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-
-      - uses: ruby/setup-ruby@v1
-        with:
-          ruby-version: '2.7'
-          bundler-cache: true
-
-      - uses: actions/download-artifact@v2
-        with:
-          name: pkg
-          path: pkg
-
-      - name: Publish to rubygems.org
-        env:
-          RUBYGEMS_API_KEY: ${{secrets.METANORMA_CI_RUBYGEMS_API_KEY}}
-        run: |
-          mkdir -p ~/.gem
-          touch ~/.gem/credentials
-          cat > ~/.gem/credentials << EOF
-          ---
-          :rubygems_api_key: ${RUBYGEMS_API_KEY}
-          EOF
-          chmod 0600 ~/.gem/credentials
-          gem signin
-          ls -l pkg/
-          for gem in pkg/*.gem; do gem push -V $gem; done
+    - uses: actions/checkout@v2
+
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: '2.7'
+        bundler-cache: true
+
+    - uses: actions/download-artifact@v2
+      with:
+        name: pkg
+        path: pkg
+
+    - name: Publish to rubygems.org
+      env:
+        RUBYGEMS_API_KEY: ${{secrets.METANORMA_CI_RUBYGEMS_API_KEY}}
+      run: |
+        mkdir -p ~/.gem
+        touch ~/.gem/credentials
+        cat > ~/.gem/credentials << EOF
+        ---
+        :rubygems_api_key: ${RUBYGEMS_API_KEY}
+        EOF
+        chmod 0600 ~/.gem/credentials
+        gem signin
+        ls -l pkg/
+        for gem in pkg/*.gem; do gem push -V $gem; done
diff --git a/lib/emf2svg/recipe.rb b/lib/emf2svg/recipe.rb
index 4a132b0c..98b82501 100644
--- a/lib/emf2svg/recipe.rb
+++ b/lib/emf2svg/recipe.rb
@@ -80,7 +80,7 @@ def target_triplet
         when /\Ax64-mingw(32|-ucrt)/
           "x64-mingw-static"
         else
-          "unknown"
+          nil
         end
     end
     # rubocop:enable Metrics/CyclomaticComplexity
@@ -96,7 +96,7 @@ def configure_defaults
       opts << "-DCMAKE_BUILD_TYPE=Release"
       opts << "-DLONLY=ON"
 
-      if not target_triplet.eql? "unknown" and not host_platform.eql? target_platform
+      unless target_triplet.nil? "unknown" or host_platform.eql? target_platform
         opts << " -DVCPKG_TARGET_TRIPLET=#{target_triplet}"
       end
 
@@ -143,8 +143,7 @@ def message(text)
     private
 
     def tmp_path
-#      @tmp_path ||= Dir.mktmpdir
-      @tmp_path = "/tmp/1"
+      @tmp_path ||= Dir.mktmpdir
     end
 
     def port_path