diff --git a/.github/workflows/flake-update.yml b/.github/workflows/flake-update.yml
index a5ca4dd..c3dcab2 100644
--- a/.github/workflows/flake-update.yml
+++ b/.github/workflows/flake-update.yml
@@ -12,7 +12,8 @@ jobs:
         uses: actions/checkout@v4.1.5
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v11
-      - name: update
+      - name: Update flake lock
+        id: update
         uses: DeterminateSystems/update-flake-lock@v21
         with:
           pr-title: "Update flake.lock" 
@@ -21,7 +22,7 @@ jobs:
             automated
       - name: merge
         run: |
-          gh pr merge "$PULL_REQUEST_NUMBER" --squash --delete-branch
+          gh pr merge ${{ steps.update.outputs.pull-request-number }} --squash --delete-branch
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}