diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 2c371b2..5afc01a 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -169,14 +169,14 @@ jobs:
         run: python -m twine check dist/pvxslibs-*.tar.*
 
       - name: Upload wheels
-        if: github.event_name=='push' && github.ref=='refs/heads/master' && matrix.piparch
+        if: env.TWINE_USERNAME && github.event_name=='push' && github.ref=='refs/heads/master' && matrix.piparch
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
         run: python -m twine upload --skip-existing dist/pvxslibs-*.whl
 
       - name: Upload source
-        if: github.event_name=='push' && github.ref=='refs/heads/master' && matrix.source
+        if: env.TWINE_USERNAME && github.event_name=='push' && github.ref=='refs/heads/master' && matrix.source
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}
@@ -373,7 +373,7 @@ jobs:
           ! ls junk/*/*/purelib
 
       - name: Upload wheels
-        if: github.event_name=='push' && github.ref=='refs/heads/master'
+        if: env.TWINE_USERNAME && github.event_name=='push' && github.ref=='refs/heads/master'
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}
           TWINE_PASSWORD: ${{ secrets.PYPI_PASSWORD }}