diff --git a/.github/workflows/python_tests.yml b/.github/workflows/python_tests.yml
index 9252de20c695..b0c0c34429f9 100644
--- a/.github/workflows/python_tests.yml
+++ b/.github/workflows/python_tests.yml
@@ -117,7 +117,7 @@ jobs:
       shell: bash -l {0}
       if: |
         (github.ref == 'refs/heads/master' || contains(github.ref, 'refs/heads/release_')) &&
-        matrix.os == 'macos-latest'
+        matrix.os == 'macos-10.15'
       run: |
         python -m awscli s3 cp python-package/dist/*.whl s3://xgboost-nightly-builds/${{ steps.extract_branch.outputs.branch }}/ --acl public-read
       env: