diff --git a/flake.lock b/flake.lock
index 1bc69bb..52e4698 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1029,6 +1029,22 @@
       }
     },
     "nixpkgs_12": {
+      "locked": {
+        "lastModified": 1761236834,
+        "narHash": "sha256-+pthv6hrL5VLW2UqPdISGuLiUZ6SnAXdd2DdUE+fV2Q=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "d5faa84122bc0a1fd5d378492efce4e289f8eac1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_13": {
       "locked": {
         "lastModified": 1615532953,
         "narHash": "sha256-SWpaGjrp/INzorEqMz3HLi6Uuk9I0KAn4YS8B4n3q5g=",
@@ -1372,6 +1388,7 @@
         "stylix": "stylix_2",
         "telebots": "telebots_2",
         "tinc-graph": "tinc-graph_2",
+        "treefmt-nix": "treefmt-nix_2",
         "voidrice": "voidrice_2",
         "wallpaper-generator": "wallpaper-generator_2",
         "wallpapers": "wallpapers_2"
@@ -1849,6 +1866,24 @@
         "type": "github"
       }
     },
+    "treefmt-nix_2": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_12"
+      },
+      "locked": {
+        "lastModified": 1766000401,
+        "narHash": "sha256-+cqN4PJz9y0JQXfAK5J1drd0U05D5fcAGhzhfVrDlsI=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "42d96e75aa56a3f70cab7e7dc4a32868db28e8fd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
+    },
     "voidrice": {
       "flake": false,
       "locked": {
@@ -1908,7 +1943,7 @@
     "wallpaper-generator_2": {
       "inputs": {
         "flake-utils": "flake-utils_4",
-        "nixpkgs": "nixpkgs_12"
+        "nixpkgs": "nixpkgs_13"
       },
       "locked": {
         "lastModified": 1615819231,
diff --git a/flake.nix b/flake.nix
index 1ceaa28..2e54f26 100644
--- a/flake.nix
+++ b/flake.nix
@@ -22,6 +22,7 @@
     stylix.url = "github:danth/stylix/release-25.11";
     telebots.url = "github:kmein/telebots";
     tinc-graph.url = "github:kmein/tinc-graph";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
     voidrice.url = "github:Lukesmithxyz/voidrice";
     wallpaper-generator.url = "github:pinpox/wallpaper-generator/v1.1";
     wallpapers.url = "github:kmein/wallpapers";
@@ -57,6 +58,7 @@
       scripts,
       tinc-graph,
       recht,
+      treefmt-nix,
       autorenkalender,
       wallpaper-generator,
       telebots,
@@ -69,6 +71,20 @@
     let
       lib = nixpkgs.lib;
       eachSupportedSystem = lib.genAttrs lib.systems.flakeExposed;
+      treefmtEval = eachSupportedSystem (
+        system:
+        treefmt-nix.lib.evalModule nixpkgs.legacyPackages.${system} (
+          { pkgs, ... }:
+          {
+            projectRootFile = "flake.nix";
+            programs.nixfmt.enable = true;
+            programs.ormolu.enable = true;
+            programs.black.enable = true;
+            programs.prettier.enable = true;
+            programs.stylua.enable = true;
+          }
+        )
+      );
     in
     {
       apps =
@@ -240,8 +256,10 @@
         # packaged from inputs
         agenix = agenix.packages.${prev.stdenv.hostPlatform.system}.default;
         alarm = scripts.packages.${prev.stdenv.hostPlatform.system}.alarm;
-        menstruation-telegram = menstruation-telegram.packages.${prev.stdenv.hostPlatform.system}.menstruation-telegram;
-        menstruation-backend = menstruation-backend.packages.${prev.stdenv.hostPlatform.system}.menstruation-backend;
+        menstruation-telegram =
+          menstruation-telegram.packages.${prev.stdenv.hostPlatform.system}.menstruation-telegram;
+        menstruation-backend =
+          menstruation-backend.packages.${prev.stdenv.hostPlatform.system}.menstruation-backend;
         telebots = telebots.packages.${prev.stdenv.hostPlatform.system}.telebots;
         hesychius = scripts.packages.${prev.stdenv.hostPlatform.system}.hesychius;
         autorenkalender = autorenkalender.packages.${prev.stdenv.hostPlatform.system}.default;
@@ -414,7 +432,10 @@
           };
         };
 
-      formatter = eachSupportedSystem (system: nixpkgs.legacyPackages.${system}.nixfmt-tree);
+      formatter = eachSupportedSystem (system: treefmtEval.${system}.config.build.wrapper);
+      checks = eachSupportedSystem (system: {
+        formatting = treefmtEval.${system}.config.build.check self;
+      });
 
       packages = eachSupportedSystem (
         system: