diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index a6b05d2..da89d2d 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -15,6 +15,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         go: ['1.18', '1.19', '1.20']
+        tags: ['', 'test_cow']
     steps:
     - name: Set up Go
       uses: actions/setup-go@v4
@@ -32,7 +33,7 @@ jobs:
       run: go build -v .
 
     - name: Test
-      run: go test -v --tags=go${{ matrix.go }}
+      run: go test -v --tags=go${{ matrix.go }},${{ matrix.tags }}
   benchmark:
     name: Benchmark
     runs-on: ubuntu-latest