diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f47ec9bd..8d0238a9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,12 +27,12 @@ jobs:
     strategy:
       matrix:
         ruby-version:
-          - 2.6
-          - 2.7
-          - 3.0
-          - 3.1
-          - 3.2
-          - 3.3
+          - '2.6'
+          - '2.7'
+          - '3.0'
+          - '3.1'
+          - '3.2'
+          - '3.3'
     steps:
       - uses: actions/checkout@v4
       - name: Setup Ruby