diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 4ae8e6d..b86001f 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,10 +13,10 @@ jobs:
         # test a range of Ruby to ensure gem works
         # keep ruby until EOL. Read more on https://endoflife.date/ruby
         ruby-version:
-          - 3.0
-          - 3.1
-          - 3.2
-          - 3.3
+          - '3.0'
+          - '3.1'
+          - '3.2'
+          - '3.3'
           - head
         # test distributions up to 4 years
         runner: