diff --git a/flake.lock b/flake.lock
index febb002..4469374 100755
--- a/flake.lock
+++ b/flake.lock
@@ -442,7 +442,8 @@
         "rust-overlay": "rust-overlay",
         "sops-nix": "sops-nix",
         "spicetify-nix": "spicetify-nix",
-        "systems": "systems"
+        "systems": "systems",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "rust-overlay": {
@@ -528,6 +529,26 @@
         "repo": "default",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709911575,
+        "narHash": "sha256-yC2iOKe0BSZAeXLNPXPrsGn5BwUTYYZESKb+OblLnXY=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "9c57261c71871d2208a6dd4394774cca226c6dbc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index c24d522..f8a2b0c 100755
--- a/flake.nix
+++ b/flake.nix
@@ -76,6 +76,10 @@
       inputs.flake-utils.follows = "flake-utils";
     };
     systems.url = "github:nix-systems/default";
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
 
     ### De-dupe flake dependencies
     crane = {
@@ -128,8 +132,11 @@
         inherit system modules;
         specialArgs = {inherit inputs;};
       };
+
+    treefmtEval = eachDefaultSystemMap (system: inputs.treefmt-nix.lib.evalModule inputs.nixpkgs.legacyPackages.${system} ./treefmt.nix);
   in {
-    formatter = eachDefaultSystemMap (system: inputs.nixpkgs.legacyPackages.${system}.alejandra);
+    formatter = eachDefaultSystemMap (system: treefmtEval.${system}.config.build.wrapper);
+    checks = eachDefaultSystemMap (system: {formatting = treefmtEval.${system}.config.build.check inputs.self;});
     packages = eachDefaultSystemMap (system: import ./pkgs inputs.nixpkgs.legacyPackages.${system});
     overlays = import ./overlays;
     nixosModules.default = ./nixos/modules;
diff --git a/home/applications/firefox/user-overrides.js b/home/applications/firefox/user-overrides.js
index 0324d2b..dee861b 100644
--- a/home/applications/firefox/user-overrides.js
+++ b/home/applications/firefox/user-overrides.js
@@ -31,5 +31,5 @@ user_pref("browser.urlbar.suggest.calculator", true);
 user_pref("apz.overscroll.enabled", true);
 user_pref("general.smoothScroll", true);
 user_pref("general.smoothScroll.msdPhysics.enabled", true);
-user_pref("general.smoothScroll.msdPhysics.motionBeginSpringConstant", 600)
+user_pref("general.smoothScroll.msdPhysics.motionBeginSpringConstant", 600);
 user_pref("mousewheel.default.delta_multiplier_y", 75);
diff --git a/home/applications/thunderbird/user-overrides.js b/home/applications/thunderbird/user-overrides.js
index 4b3ed29..c5120b4 100644
--- a/home/applications/thunderbird/user-overrides.js
+++ b/home/applications/thunderbird/user-overrides.js
@@ -6,7 +6,6 @@ user_pref("browser.cache.memory.capacity", 1);
 user_pref("privacy.clearOnShutdown.cache", false);
 user_pref("mail.imap.use_disk_cache2", true);
 
-
 // View related.
 // Makes messages prettier.
 user_pref("permissions.default.image", 1);
diff --git a/treefmt.nix b/treefmt.nix
new file mode 100644
index 0000000..5b824e4
--- /dev/null
+++ b/treefmt.nix
@@ -0,0 +1,19 @@
+{
+  projectRootFile = "flake.nix";
+
+  ### nix
+  programs.deadnix.enable = true;
+  programs.statix.enable = true;
+  programs.alejandra.enable = true;
+
+  ### shell
+  programs.shellcheck.enable = true;
+  programs.shfmt.enable = true;
+
+  ### toml
+  programs.taplo.enable = true;
+
+  ### misc
+  programs.prettier.enable = true;
+  settings.formatter.prettier.excludes = ["secrets.yaml"];
+}