diff --git a/flake/dev/default.nix b/flake/dev/default.nix
index 4cc3d37c..2fc3ba64 100644
--- a/flake/dev/default.nix
+++ b/flake/dev/default.nix
@@ -4,81 +4,6 @@
     ./nixpkgs-and-dev-nixpkgs-version-consistency.nix
     ./packages.nix
     ./pre-commit.nix
+    ./treefmt.nix
   ];
-
-  perSystem =
-    { pkgs, ... }:
-    {
-      # TODO: consider using https://flake.parts/options/treefmt-nix.html
-      formatter = pkgs.treefmt.withConfig {
-        runtimeInputs = with pkgs; [
-          # keep-sorted start
-          biome
-          keep-sorted
-          nixfmt-rfc-style
-          ruff
-          stylish-haskell
-          # keep-sorted end
-        ];
-
-        settings = {
-          on-unmatched = "info";
-          tree-root-file = "flake.nix";
-
-          formatter = {
-            # keep-sorted start block=yes
-            biome = {
-              command = "biome";
-              options = [
-                "format"
-                "--write"
-                "--no-errors-on-unmatched"
-                "--config-path"
-                (pkgs.writers.writeJSON "biome.json" {
-                  formatter = {
-                    indentStyle = "space";
-                    indentWidth = 2;
-                    lineWidth = 80;
-                  };
-                })
-              ];
-              includes = [
-                "*.css"
-                "*.js"
-                "*.json"
-              ];
-              excludes = [
-                # Contains custom syntax that biome can't handle
-                "modules/swaync/base.css"
-              ];
-            };
-            keep-sorted = {
-              command = "keep-sorted";
-              includes = [ "*" ];
-            };
-            nixfmt = {
-              command = "nixfmt";
-              options = [ "--width=80" ];
-              includes = [ "*.nix" ];
-            };
-            ruff = {
-              command = "ruff";
-              options = [
-                "--config"
-                (pkgs.writers.writeTOML "ruff.toml" {
-                  line-length = 80;
-                })
-                "format"
-              ];
-              includes = [ "*.py" ];
-            };
-            stylish-haskell = {
-              command = "stylish-haskell";
-              includes = [ "*.hx" ];
-            };
-            # keep-sorted end
-          };
-        };
-      };
-    };
 }
diff --git a/flake/dev/dev-shell.nix b/flake/dev/dev-shell.nix
index d66479d2..a125e398 100644
--- a/flake/dev/dev-shell.nix
+++ b/flake/dev/dev-shell.nix
@@ -44,15 +44,14 @@
           # Install git-hooks when activating the shell
           shellHook = config.pre-commit.installationScript;
 
-          packages =
-            [
-              stylix-check
-              build-and-run-docs
-              inputs'.home-manager.packages.default
-              config.formatter
-            ]
-            ++ config.pre-commit.settings.enabledPackages
-            ++ config.formatter.runtimeInputs;
+          packages = [
+            stylix-check
+            build-and-run-docs
+            inputs'.home-manager.packages.default
+            config.formatter
+          ] ++ config.pre-commit.settings.enabledPackages;
+
+          inputsFrom = [ config.treefmt.build.devShell ];
         };
 
         ghc = pkgs.mkShell {
diff --git a/flake/dev/flake.lock b/flake/dev/flake.lock
index 64f1d79d..3be6632b 100644
--- a/flake/dev/flake.lock
+++ b/flake/dev/flake.lock
@@ -101,7 +101,28 @@
         "dev-nixpkgs": "dev-nixpkgs",
         "flake-compat": "flake-compat",
         "git-hooks": "git-hooks",
-        "home-manager": "home-manager"
+        "home-manager": "home-manager",
+        "treefmt-nix": "treefmt-nix"
+      }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "dev-nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1750931469,
+        "narHash": "sha256-0IEdQB1nS+uViQw4k3VGUXntjkDp7aAlqcxdewb/hAc=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "ac8e6f32e11e9c7f153823abc3ab007f2a65d3e1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
       }
     }
   },
diff --git a/flake/dev/flake.nix b/flake/dev/flake.nix
index 214a83e0..13e038ee 100644
--- a/flake/dev/flake.nix
+++ b/flake/dev/flake.nix
@@ -46,6 +46,11 @@
       url = "github:nix-community/home-manager";
       inputs.nixpkgs.follows = "dev-nixpkgs";
     };
+
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "dev-nixpkgs";
+    };
     # keep-sorted end
   };
 
diff --git a/flake/dev/treefmt.nix b/flake/dev/treefmt.nix
new file mode 100644
index 00000000..c899074d
--- /dev/null
+++ b/flake/dev/treefmt.nix
@@ -0,0 +1,41 @@
+{ inputs, ... }:
+{
+  imports = [ inputs.treefmt-nix.flakeModule ];
+
+  perSystem.treefmt = {
+    projectRootFile = "flake.nix";
+
+    programs = {
+      # keep-sorted start block=yes newline_separated=no
+      biome = {
+        enable = true;
+        settings.formatter = {
+          indentStyle = "space";
+          indentWidth = 2;
+          lineWidth = 80;
+        };
+        includes = [
+          "*.css"
+          "*.js"
+          "*.json"
+        ];
+        excludes = [
+          # Contains custom syntax that biome can't handle
+          "modules/swaync/base.css"
+        ];
+      };
+      keep-sorted.enable = true;
+      nixfmt = {
+        enable = true;
+        width = 80;
+      };
+      ruff-format = {
+        enable = true;
+        lineLength = 80;
+      };
+      shfmt.enable = true;
+      stylish-haskell.enable = true;
+      # keep-sorted end
+    };
+  };
+}