diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5416484..519fd8a 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -3,11 +3,21 @@ name: test
 on: [push, pull_request]
 
 jobs:
-  build:
+  ruby-versions:
+    runs-on: ubuntu-latest
+    outputs:
+      versions: ${{ steps.versions.outputs.value }}
+    steps:
+      - id: versions
+        run: |
+          versions=$(curl -s 'https://cache.ruby-lang.org/pub/misc/ci_versions/cruby.json' | jq -c '. - ["2.7"]')
+          echo "::set-output name=value::${versions}"
+  test:
+    needs: ruby-versions
     name: build (${{ matrix.ruby }} / ${{ matrix.os }})
     strategy:
       matrix:
-        ruby: [ head ]
+        ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
         os: [ ubuntu-latest, macos-latest ]
     runs-on: ${{ matrix.os }}
     steps: