diff --git a/.github/workflows/update-vendor-hash.yml b/.github/workflows/update-vendor-hash.yml
index 98d01ec..64951eb 100644
--- a/.github/workflows/update-vendor-hash.yml
+++ b/.github/workflows/update-vendor-hash.yml
@@ -11,6 +11,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
         with:
+          ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
       - name: Install Nix
         uses: cachix/install-nix-action@v22