diff --git a/flake.lock b/flake.lock
index e8d4a2e..bf07e4d 100644
--- a/flake.lock
+++ b/flake.lock
@@ -80,7 +80,8 @@
         "fenix": "fenix",
         "flake-utils": "flake-utils",
         "nix-vm-test": "nix-vm-test",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "rust-analyzer-src": {
@@ -114,6 +115,26 @@
         "repo": "default",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1743748085,
+        "narHash": "sha256-uhjnlaVTWo5iD3LXics1rp9gaKgDRQj6660+gbUU3cE=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "815e4121d6a5d504c0f96e5be2dd7f871e4fd99d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index 1e84d67..2686434 100644
--- a/flake.nix
+++ b/flake.nix
@@ -10,9 +10,12 @@
     nix-vm-test.url = "github:numtide/nix-vm-test";
     nix-vm-test.inputs.nixpkgs.follows = "nixpkgs";
     nix-vm-test.inputs.flake-utils.follows = "flake-utils";
+
+    treefmt-nix.url = "github:numtide/treefmt-nix";
+    treefmt-nix.inputs.nixpkgs.follows = "nixpkgs";
   };
 
-  outputs = { self, nixpkgs, flake-utils, nix-vm-test, ... }@inputs:
+  outputs = { self, nixpkgs, flake-utils, nix-vm-test, treefmt-nix, ... }@inputs:
     nixpkgs.lib.foldl (a: b: nixpkgs.lib.recursiveUpdate a b) { } [
 
 
@@ -86,6 +89,8 @@
               nix-vm-test.overlays.default
             ];
           };
+
+          treefmtEval = treefmt-nix.lib.evalModule pkgs ./treefmt.nix;
         in
         {
           packages.package-deb = pkgs.callPackage ./pkgs/package-deb.nix {
@@ -152,26 +157,15 @@
           checks = {
             systemd-rosenpass = pkgs.testers.runNixOSTest ./tests/systemd/rosenpass.nix;
             systemd-rp = pkgs.testers.runNixOSTest ./tests/systemd/rp.nix;
-
-            cargo-fmt = pkgs.runCommand "check-cargo-fmt"
-              { inherit (self.devShells.${system}.default) nativeBuildInputs buildInputs; } ''
-              cargo fmt --manifest-path=${./.}/Cargo.toml --check --all && touch $out
-            '';
-            nixpkgs-fmt = pkgs.runCommand "check-nixpkgs-fmt"
-              { nativeBuildInputs = [ pkgs.nixpkgs-fmt ]; } ''
-              nixpkgs-fmt --check ${./.} && touch $out
-            '';
-            prettier-check = pkgs.runCommand "check-with-prettier"
-              { nativeBuildInputs = [ pkgs.nodePackages.prettier ]; } ''
-              cd ${./.} && prettier --check . && touch $out
-            '';
+            formatting = treefmtEval.config.build.check self;
           } // pkgs.lib.optionalAttrs (system == "x86_64-linux") (import ./tests/legacy-distro-packaging.nix {
             inherit pkgs;
             rosenpass-deb = self.packages.${system}.package-deb;
             rosenpass-rpm = self.packages.${system}.package-rpm;
           });
 
-          formatter = pkgs.nixpkgs-fmt;
+          # for `nix fmt`
+          formatter = treefmtEval.config.build.wrapper;
         }))
     ];
 }
diff --git a/treefmt.nix b/treefmt.nix
new file mode 100644
index 0000000..a79c8f3
--- /dev/null
+++ b/treefmt.nix
@@ -0,0 +1,30 @@
+{ pkgs, ... }:
+{
+  # Used to find the project root
+  projectRootFile = "flake.nix";
+  programs.nixfmt.enable = true;
+  programs.prettier = {
+    enable = true;
+    includes = [
+      "*.css"
+      "*.html"
+      "*.js"
+      "*.json"
+      "*.json5"
+      "*.md"
+      "*.mdx"
+      "*.toml"
+      "*.yaml"
+      "*.yml"
+    ];
+    excludes = [
+      "supply-chain/*"
+    ];
+    settings = {
+      plugins = [
+        "${pkgs.nodePackages.prettier-plugin-toml}/lib/node_modules/prettier-plugin-toml/lib/index.js"
+      ];
+    };
+  };
+  programs.rustfmt.enable = true;
+}