diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3f339cc..008200f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.9, 3.10, 3.11]
+        python-version: ['3.9', '3.10', '3.11']
     steps:
     - name: Set environments from secrets
       run: |