1 files changed, 17 insertions, 2 deletions
diff --git a/flake.nix b/flake.nix
index fde7c88..37b0a77 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,10 +8,20 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+
+    # this can be removed with `inputs.treefmt-nix.follows = ""`
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
-    { nixpkgs, ... }:
+    {
+      self,
+      nixpkgs,
+      treefmt-nix,
+    }:
     let
       inherit (nixpkgs) lib;
       systems = [
@@ -23,8 +33,13 @@
 
       forAllSystems = lib.genAttrs systems;
       nixpkgsFor = forAllSystems (system: nixpkgs.legacyPackages.${system});
+      treefmtFor = forAllSystems (system: treefmt-nix.lib.evalModule nixpkgsFor.${system} ./treefmt.nix);
     in
     {
+      checks = forAllSystems (system: {
+        treefmt = treefmtFor.${system}.config.build.check self;
+      });
+
       packages = forAllSystems (
         system:
         let
@@ -43,7 +58,7 @@
         pkgs' // { default = pkgs'.treefetch; }
       );
 
-      formatter = forAllSystems (system: nixpkgsFor.${system}.nixfmt-rfc-style);
+      formatter = forAllSystems (system: treefmtFor.${system}.config.build.wrapper);
 
       templates = import ./templates;
     };