diff --git a/.github/workflows/update.yml b/.github/workflows/update.yml
index 5b4ccb3..718c8a7 100644
--- a/.github/workflows/update.yml
+++ b/.github/workflows/update.yml
@@ -13,7 +13,7 @@ jobs:
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v1
       - name: Update flake.lock
-        uses: DeterminateSystems/update-flake-lock@vX
+        uses: DeterminateSystems/update-flake-lock@v21
         with:
           token: ${{ secrets.GH_TOKEN_FOR_UPDATES }}
           commit-msg: "update"