diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 3b36deb5..dfe7dc6f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -702,7 +702,7 @@ jobs:
           export MSI_FILENAME="${GITHUB_WORKSPACE}/gam-${GAMVERSION}-windows-${GAM_ARCHIVE_ARCH}.msi"
           # auto-generate a lib.wxs based on the files PyInstaller created for the lib/ directory
           /c/Program\ Files\ \(x86\)/WiX\ Toolset\ v3.14/bin/heat.exe dir "${gampath}/lib" -ke -srd -cg Lib -gg -dr lib -directoryid lib -out lib-fixme.wxs
-          $python tools/gen-wix-xml-filelist.py lib.wxs
+          $PYTHON tools/gen-wix-xml-filelist.py lib.wxs
           echo "-- begin lib.wxs --"
           cat lib.wxs
           echo "-- end lib.wxs --"