diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index 70a440d..7cf01e1 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v3
     - name: create version.h
       run: |
-        git_hash=$(git rev-parse --short "$GITHUB_SHA")
+        git_hash=$(git rev-parse --short "${{ github.event.pull_request.head.sha }}")
         cat <<EOF > ./source/version.h
         #pragma once
         #define MODULE_VERSION_EXTRA " (nightly-$git_hash)"
@@ -29,4 +29,4 @@ jobs:
     - uses: actions/upload-artifact@master
       with:
        name: binary
-       path: "*.wms"
\ No newline at end of file
+       path: "*.wms"