diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 401589cd8..d83cff5cd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -3,58 +3,41 @@ name: Build and run tests
 on: [push, pull_request]
 
 jobs:
-  test-linux:
-    runs-on: ubuntu-latest
+  test:
+    strategy:
+      matrix:
+        runner:
+          - ubuntu-20.04
+          - macOS-10.15
+    runs-on: ${{ matrix.runner }}
     steps:
 
     - uses: actions/checkout@v2
 
-    - name: Install dependencies
+    - name: Install dependencies (Linux)
+      if: runner.os == 'Linux'
       run: |
         sudo apt-get update
         sudo apt-get install g++ gperf build-essential bison flex libreadline-dev gawk tcl-dev libffi-dev git graphviz xdot pkg-config python python3 libboost-system-dev libboost-python-dev libboost-filesystem-dev zlib1g-dev
 
-    - name: Get iverilog
-      run: |
-        git clone git://github.com/steveicarus/iverilog.git
-
-    - name: Cache iverilog
-      id: cache-iverilog
-      uses: actions/cache@v2
-      with:
-        path: iverilog-bin
-        key: ${{ runner.os }}-${{ hashFiles('iverilog/.git/refs/heads/master') }}
-
-    - name: Build iverilog
-      if: steps.cache-iverilog.outputs.cache-hit != 'true'
-      run: |
-        mkdir iverilog-bin
-        cd iverilog
-        autoconf
-        CC=gcc CXX=g++ ./configure --prefix=$PWD/../iverilog-bin
-        make -j$(nproc)
-        make install
-
-    - name: Build yosys
-      run: |
-        make -j$(nproc)
-
-    - name: Run tests
-      run: |
-        PATH=$PWD/iverilog-bin/bin:$PATH make -j$(nproc) test
-
-  test-osx:
-    runs-on: macos-latest
-    steps:
-
-    - uses: actions/checkout@v2
-
-    - name: Install dependencies
+    - name: Install dependencies (macOS)
+      if: runner.os == 'macOS'
       run: |
         brew update
         brew tap Homebrew/bundle
         brew bundle
 
+    - name: Setup environment (Linux)
+      if: runner.os == 'Linux'
+      run: |
+        echo "procs=$(nproc)" >> $GITHUB_ENV
+
+    - name: Setup environment (macOS)
+      if: runner.os == 'macOS'
+      run: |
+        echo "$(brew --prefix bison)/bin" >> $GITHUB_PATH
+        echo "procs=$(sysctl -n hw.ncpu)" >> $GITHUB_ENV
+
     - name: Get iverilog
       run: |
         git clone git://github.com/steveicarus/iverilog.git
@@ -69,19 +52,17 @@ jobs:
     - name: Build iverilog
       if: steps.cache-iverilog.outputs.cache-hit != 'true'
       run: |
-        export PATH="$(brew --prefix bison)/bin:$PATH"
         mkdir iverilog-bin
         cd iverilog
         autoconf
         CC=gcc CXX=g++ ./configure --prefix=$PWD/../iverilog-bin
-        make -j$(sysctl -n hw.ncpu)
+        make -j${{ env.procs }}
         make install
 
     - name: Build yosys
       run: |
-        export PATH="$(brew --prefix bison)/bin:$PATH"
-        make -j$(sysctl -n hw.ncpu)
+        make -j${{ env.procs }}
 
     - name: Run tests
       run: |
-        PATH=$PWD/iverilog-bin/bin:$PATH make -j$(sysctl -n hw.ncpu) test
+        PATH=$PWD/iverilog-bin/bin:$PATH make -j${{ env.procs }} test