diff --git a/.github/workflows/fmt.yaml b/.github/workflows/fmt.yaml
index 1bffffa..6f8d3f4 100644
--- a/.github/workflows/fmt.yaml
+++ b/.github/workflows/fmt.yaml
@@ -22,4 +22,4 @@ jobs:
           extra_nix_config: |
             experimental-features = nix-command flakes
 
-      - run: nix-shell -p nixpkgs-fmt --run 'nixpkgs-fmt .'
+      - run: nix-shell -p nixpkgs-fmt --run 'nixpkgs-fmt . --check'