diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index dc673d3..63c6fbc 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.8,3.9,3.10]
+        python-version: ['3.8','3.9','3.10']
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}