diff --git a/flake.nix b/flake.nix
index 6fb5637..75bd6b3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -123,5 +123,6 @@
       ];
     };
     devShell.${system} = self.devShells.${system}.default; # compatibility
+    formatter.${system} = nixpkgs.legacyPackages.${system}.nixfmt-tree; # TODO: migrate to stable with 25.05
   };
 }