diff --git a/SwarselSystems.org b/SwarselSystems.org
index b61752f..5acc547 100644
--- a/SwarselSystems.org
+++ b/SwarselSystems.org
@@ -561,6 +561,7 @@ A short overview over each input and what it does:
         url = "github:astro/microvm.nix";
         inputs.nixpkgs.follows = "nixpkgs";
       };
+      treefmt-nix.url = "github:numtide/treefmt-nix";
 
     };
     outputs =
@@ -1375,6 +1376,7 @@ Lastly, in the =perSystem= attribute set, we see that it is actually passed some
               nixpkgs-fmt.enable = true;
               statix.enable = true;
               trim-trailing-whitespace.enable = true;
+              treefmt.enable = true;
 
               destroyed-symlinks = {
                 enable = true;
@@ -1583,10 +1585,32 @@ Otherwise, I define the function =mkTemplates= here which builds a named attribu
 Defines a formatter that can be called using =nix flake format=. While a nice utility, I have stronger tools to perform this job.
 
 #+begin_src nix-ts :tangle nix/formatter.nix
-  _:
+  { inputs, ... }:
   {
+    imports = [
+      inputs.treefmt-nix.flakeModule
+    ];
+
     perSystem = { pkgs, ... }: {
-      formatter = pkgs.nixpkgs-fmt;
+      # formatter = pkgs.nixpkgs-fmt;
+      # formatter is set by treefmt to:
+      # formatter = lib.mkIf config.treefmt.flakeFormatter (lib.mkDefault config.treefmt.build.wrapper);
+      treefmt = {
+        projectRootFile = "flake.nix";
+        programs = {
+          nixfmt = {
+            enable = true;
+            package = pkgs.nixpkgs-fmt;
+          };
+          deadnix.enable = true;
+          statix.enable = true;
+          shellcheck.enable = true;
+        };
+        settings.formatter.shellcheck.options = [
+          "--shell"
+          "bash"
+        ];
+      };
     };
   }
 
@@ -22386,7 +22410,7 @@ This adds support for Terraform configuration files. I need this at work.
   (add-hook 'terraform-mode-hook #'outline-minor-mode)
 
 #+end_src
-*** nixpkgs-fmt
+*** nix formatting
 :PROPERTIES:
 :CUSTOM_ID: h:5ca7484b-b9d6-4023-88d1-a1e37d5df249
 :END:
diff --git a/flake.lock b/flake.lock
index 10b1bfe..2c8ba1c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -10577,6 +10577,22 @@
       }
     },
     "nixpkgs_82": {
+      "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_83": {
       "locked": {
         "lastModified": 1754800730,
         "narHash": "sha256-HfVZCXic9XLBgybP0318ym3cDnGwBs/+H5MgxFVYF4I=",
@@ -12582,6 +12598,7 @@
         "swarsel-modules": "swarsel-modules_6",
         "swarsel-nix": "swarsel-nix_3",
         "systems": "systems_64",
+        "treefmt-nix": "treefmt-nix_3",
         "vbc-nix": "vbc-nix_8",
         "zjstatus": "zjstatus_8"
       }
@@ -16052,6 +16069,24 @@
         "type": "github"
       }
     },
+    "treefmt-nix_3": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_82"
+      },
+      "locked": {
+        "lastModified": 1762938485,
+        "narHash": "sha256-AlEObg0syDl+Spi4LsZIBrjw+snSVU4T8MOeuZJUJjM=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "5b4ee75aeefd1e2d5a1cc43cf6ba65eba75e83e4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
+    },
     "vbc-nix": {
       "inputs": {
         "nixpkgs": [
@@ -16628,7 +16663,7 @@
       "inputs": {
         "crane": "crane_17",
         "flake-utils": "flake-utils_29",
-        "nixpkgs": "nixpkgs_82",
+        "nixpkgs": "nixpkgs_83",
         "rust-overlay": "rust-overlay_17"
       },
       "locked": {
diff --git a/flake.nix b/flake.nix
index 065ad8b..363b431 100644
--- a/flake.nix
+++ b/flake.nix
@@ -102,6 +102,7 @@
       url = "github:astro/microvm.nix";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    treefmt-nix.url = "github:numtide/treefmt-nix";
 
   };
   outputs =
diff --git a/nix/devshell.nix b/nix/devshell.nix
index a32661b..8d8274c 100644
--- a/nix/devshell.nix
+++ b/nix/devshell.nix
@@ -27,6 +27,7 @@
             nixpkgs-fmt.enable = true;
             statix.enable = true;
             trim-trailing-whitespace.enable = true;
+            treefmt.enable = true;
 
             destroyed-symlinks = {
               enable = true;
diff --git a/nix/formatter.nix b/nix/formatter.nix
index c00f3f2..cf3ce6a 100644
--- a/nix/formatter.nix
+++ b/nix/formatter.nix
@@ -1,6 +1,28 @@
-_:
+{ inputs, ... }:
 {
+  imports = [
+    inputs.treefmt-nix.flakeModule
+  ];
+
   perSystem = { pkgs, ... }: {
-    formatter = pkgs.nixpkgs-fmt;
+    # formatter = pkgs.nixpkgs-fmt;
+    # formatter is set by treefmt to:
+    # formatter = lib.mkIf config.treefmt.flakeFormatter (lib.mkDefault config.treefmt.build.wrapper);
+    treefmt = {
+      projectRootFile = "flake.nix";
+      programs = {
+        nixfmt = {
+          enable = true;
+          package = pkgs.nixpkgs-fmt;
+        };
+        deadnix.enable = true;
+        statix.enable = true;
+        shellcheck.enable = true;
+      };
+      settings.formatter.shellcheck.options = [
+        "--shell"
+        "bash"
+      ];
+    };
   };
 }