diff --git a/README.md b/README.md
index 5a52d25..0bc2c89 100644
--- a/README.md
+++ b/README.md
@@ -2,11 +2,11 @@
 
 Flake module which allows generating a `.gitlab-ci.yml` from Nix.
 This allows easily using any Nix package in CI.
-Also makes it possible to split CI parts in a separate module 
+Also makes it possible to split CI parts in a separate module
 which can be imported in multiple projects.
 
-
 ## Usage
+
 ```nix
 # flake.nix
 {
@@ -37,6 +37,7 @@ which can be imported in multiple projects.
   }
 }
 ```
+
 ```yaml
 # .gitlab-ci.yml
 include:
diff --git a/flake.lock b/flake.lock
index c08280e..f1d2356 100644
--- a/flake.lock
+++ b/flake.lock
@@ -149,24 +149,6 @@
         "type": "github"
       }
     },
-    "flake-utils_2": {
-      "inputs": {
-        "systems": "systems"
-      },
-      "locked": {
-        "lastModified": 1701680307,
-        "narHash": "sha256-kAuep2h5ajznlPMD9rnQyffWG8EM/C73lejGofXvdM8=",
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "rev": "4022d587cbbfd70fe950c1e2083a02621806a725",
-        "type": "github"
-      },
-      "original": {
-        "owner": "numtide",
-        "repo": "flake-utils",
-        "type": "github"
-      }
-    },
     "gitignore": {
       "inputs": {
         "nixpkgs": [
@@ -175,11 +157,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1703887061,
-        "narHash": "sha256-gGPa9qWNc6eCXT/+Z5/zMkyYOuRZqeFZBDbopNZQkuY=",
+        "lastModified": 1709087332,
+        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
         "owner": "hercules-ci",
         "repo": "gitignore.nix",
-        "rev": "43e1aa1308018f37118e34d3a9cb4f5e75dc11d5",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
         "type": "github"
       },
       "original": {
@@ -296,16 +278,16 @@
     },
     "nixpkgs-stable_2": {
       "locked": {
-        "lastModified": 1704874635,
-        "narHash": "sha256-YWuCrtsty5vVZvu+7BchAxmcYzTMfolSPP5io8+WYCg=",
+        "lastModified": 1720386169,
+        "narHash": "sha256-NGKVY4PjzwAa4upkGtAMz1npHGoRzWotlSnVlqI40mo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "3dc440faeee9e889fe2d1b4d25ad0f430d449356",
+        "rev": "194846768975b7ad2c4988bdb82572c00222c0d7",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-23.11",
+        "ref": "nixos-24.05",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -328,11 +310,11 @@
     },
     "nixpkgs_3": {
       "locked": {
-        "lastModified": 1704842529,
-        "narHash": "sha256-OTeQA+F8d/Evad33JMfuXC89VMetQbsU4qcaePchGr4=",
+        "lastModified": 1719082008,
+        "narHash": "sha256-jHJSUH619zBQ6WdC21fFAlDxHErKVDJ5fpN0Hgx4sjs=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "eabe8d3eface69f5bb16c18f8662a702f50c20d5",
+        "rev": "9693852a2070b398ee123a329e68f0dab5526681",
         "type": "github"
       },
       "original": {
@@ -342,20 +324,35 @@
         "type": "github"
       }
     },
+    "nixpkgs_4": {
+      "locked": {
+        "lastModified": 1725103162,
+        "narHash": "sha256-Ym04C5+qovuQDYL/rKWSR+WESseQBbNAe5DsXNx5trY=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "12228ff1752d7b7624a54e9c1af4b222b3c1073b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "pre-commit-hooks": {
       "inputs": {
         "flake-compat": "flake-compat_3",
-        "flake-utils": "flake-utils_2",
         "gitignore": "gitignore",
         "nixpkgs": "nixpkgs_3",
         "nixpkgs-stable": "nixpkgs-stable_2"
       },
       "locked": {
-        "lastModified": 1705229514,
-        "narHash": "sha256-itILy0zimR/iyUGq5Dgg0fiW8plRDyxF153LWGsg3Cw=",
+        "lastModified": 1725513492,
+        "narHash": "sha256-tyMUA6NgJSvvQuzB7A1Sf8+0XCHyfSPRx/b00o6K0uo=",
         "owner": "cachix",
         "repo": "pre-commit-hooks.nix",
-        "rev": "ffa9a5b90b0acfaa03b1533b83eaf5dead819a05",
+        "rev": "7570de7b9b504cfe92025dd1be797bf546f66528",
         "type": "github"
       },
       "original": {
@@ -371,25 +368,11 @@
         "flake-parts": "flake-parts",
         "nixpkgs": "nixpkgs_2",
         "pre-commit-hooks": "pre-commit-hooks",
-        "systems": "systems_2"
+        "systems": "systems",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "systems": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
-    },
-    "systems_2": {
       "locked": {
         "lastModified": 1689347949,
         "narHash": "sha256-12tWmuL2zgBgZkdoB6qXZsgJEH9LR3oUgpaQq2RbI80=",
@@ -403,6 +386,24 @@
         "repo": "default-linux",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_4"
+      },
+      "locked": {
+        "lastModified": 1725271838,
+        "narHash": "sha256-VcqxWT0O/gMaeWTTjf1r4MOyG49NaNxW4GHTO3xuThE=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "9fb342d14b69aefdf46187f6bb80a4a0d97007cd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index 973b4ff..3eaa120 100644
--- a/flake.nix
+++ b/flake.nix
@@ -7,6 +7,7 @@
     flake-parts.lib.mkFlake {inherit inputs;} {
       imports = [
         inputs.devenv.flakeModule
+        inputs.treefmt-nix.flakeModule
         ./lib/flakeModule.nix
       ];
       systems = import systems;
@@ -14,16 +15,27 @@
       perSystem = {
         pkgs,
         inputs',
+        config,
         ...
       }: rec {
-        formatter = pkgs.alejandra;
+        treefmt = {
+          projectRootFile = "flake.nix";
+          programs = {
+            alejandra.enable = true;
+            mdformat.enable = true;
+            yamlfmt.enable = true;
+          };
+        };
         devenv.shells.default = {
           containers = pkgs.lib.mkForce {};
           packages = with pkgs; [dive skopeo];
 
           pre-commit = {
             hooks = {
-              alejandra.enable = true;
+              treefmt = {
+                enable = true;
+                packageOverrides.treefmt = config.treefmt.build.wrapper;
+              };
             };
           };
         };
@@ -157,6 +169,7 @@
       inputs.pre-commit-hooks.follows = "pre-commit-hooks";
     };
     pre-commit-hooks.url = "github:cachix/pre-commit-hooks.nix";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
     attic = {
       url = "gitlab:TECHNOFAB/attic";
       inputs.nixpkgs.follows = "nixpkgs";
diff --git a/gitlab-ci.yml b/gitlab-ci.yml
index 71dc45c..f1cb469 100644
--- a/gitlab-ci.yml
+++ b/gitlab-ci.yml
@@ -4,11 +4,9 @@
 variables:
   # latest | latest-cachix | latest-attic etc.
   NIX_CI_IMAGE_TAG: latest
-
 stages:
   - build
   - trigger
-
 nix-ci:build:
   stage: build
   image: registry.gitlab.com/technofab/nix-gitlab-ci/nix-ci:${NIX_CI_IMAGE_TAG}
@@ -24,7 +22,6 @@ nix-ci:build:
   artifacts:
     paths:
       - generated-gitlab-ci.yml
-
 nix-ci:trigger:
   stage: trigger
   needs: