diff --git a/.github/workflows/pythonpackage.yml b/.github/workflows/pythonpackage.yml
index a809421..7528371 100644
--- a/.github/workflows/pythonpackage.yml
+++ b/.github/workflows/pythonpackage.yml
@@ -10,7 +10,7 @@
       max-parallel: 6
       fail-fast: false
       matrix:
-        python-version: [3.9, 3.10]
+        python-version: ['3.9', '3.10']
         r-version: [release]
         os: [windows-latest, macOS-latest, ubuntu-latest]
     steps: