diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index f9db60ef5..ea5327727 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: macos-latest
     strategy:
       matrix:
-        ruby: [ 3.0, 2.7, 2.6, ruby-head ]
+        ruby: [ '3.0', 2.7, 2.6, ruby-head ]
     steps:
     - uses: actions/checkout@v2
     - uses: ruby/setup-ruby@v1
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index d2843c9c3..e2eb52d74 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -7,7 +7,7 @@ jobs:
     runs-on: windows-latest
     strategy:
       matrix:
-        ruby: [ 3.0, 2.7, 2.6, ruby-head ]
+        ruby: [ '3.0', 2.7, 2.6, ruby-head ]
     steps:
     - uses: actions/checkout@v2
     - uses: ruby/setup-ruby@v1