diff --git a/.github/workflows/guix-build.yml b/.github/workflows/guix-build.yml
index 130d215263..332feadda1 100644
--- a/.github/workflows/guix-build.yml
+++ b/.github/workflows/guix-build.yml
@@ -11,6 +11,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1