diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 8f8a7ff3..ae21c7fe 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -10,8 +10,8 @@ jobs:
       matrix:
         ruby:
           - '3.0'
-          - 3.1
-          - 3.2
+          - '3.1'
+          - '3.2'
           - jruby
           - truffleruby-head
     name: Ruby ${{ matrix.ruby }}