diff --git a/.github/workflows/matrix-and-codecov-on-merge-to-main.yml b/.github/workflows/matrix-and-codecov-on-merge-to-main.yml
index c2bf183..ff207af 100644
--- a/.github/workflows/matrix-and-codecov-on-merge-to-main.yml
+++ b/.github/workflows/matrix-and-codecov-on-merge-to-main.yml
@@ -17,6 +17,7 @@ jobs:
       project: diffpy.srxplanar
       c_extension: false
       headless: false
+      python_version: 3.13
       run: |
         pip install diffpy.srxconfutils