diff --git a/flake.nix b/flake.nix
index 44fa094..a727b66 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,17 +2,20 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     utils.url = "github:numtide/flake-utils";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
   };
 
   outputs =
-    { nixpkgs, utils, ... }:
+    { nixpkgs, utils, treefmt-nix,... }:
     utils.lib.eachDefaultSystem (
       system:
       let
         pkgs = import nixpkgs { inherit system; };
+        treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
         inherit (pkgs) mkShell;
       in
-      {
+      rec {
+        formatter = treefmtEval.config.build.wrapper;
         devShell = mkShell {
           buildInputs = with pkgs; [
             nodejs
@@ -20,6 +23,8 @@
           ];
         };
 
+        devShells.default = devShell;
+
         NPM_CONFIG_REGISTRY = "https://registry.npmmirror.com";
       }
     );