diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 88196b8..536948b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.9, 3.10, 3.11]
+        python-version: ['3.9', '3.10', '3.11']
 
     steps:
     - uses: actions/checkout@v2