diff --git a/flake.nix b/flake.nix
index e93f8c2..641a858 100644
--- a/flake.nix
+++ b/flake.nix
@@ -153,6 +153,7 @@
 
           # nix
           deadnix.enable = true;
+          nixfmt-rfc-style.enable = true;
 
           # python
           pyright.enable = true;
@@ -189,5 +190,7 @@
       shellHook = self.checks.${system}.pre-commit.shellHook;
     };
     devShell.${system} = self.devShells.${system}.default; # compatibility
+
+    formatter.${system} = pkgs.nixfmt-tree;
   };
 }