diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 25f09d8b..ea78321f 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -16,12 +16,12 @@ jobs:
         run: |
           if [[ "${{ github.event_name }}" == 'push' && "${{ github.ref }}" == 'refs/heads/master' ]]; then
             # Push to master branch
-            echo "matrix=[3.7, 3.9, 3.10, 3.11]" >> $GITHUB_OUTPUT
+            echo 'matrix=["3.7", "3.9", "3.10", "3.11"]' >> $GITHUB_OUTPUT
           elif [[ "${{ github.event_name }}" == 'pull_request' && "${{ github.event.pull_request.base.ref }}" == 'master' ]]; then
             # PR to master branch
-            echo "matrix=[3.7, 3.9, 3.10, 3.11]" >> $GITHUB_OUTPUT
+            echo 'matrix=["3.7", "3.9", "3.10", "3.11"]' >> $GITHUB_OUTPUT
           else
-            echo "matrix=[3.9]" >> $GITHUB_OUTPUT
+            echo 'matrix=["3.9"]' >> $GITHUB_OUTPUT
           fi
 
   build: