diff --git a/flake.lock b/flake.lock
index c5bab68e..9881c4d6 100644
--- a/flake.lock
+++ b/flake.lock
@@ -207,12 +207,29 @@
         "type": "github"
       }
     },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1733097829,
+        "narHash": "sha256-9hbb1rqGelllb4kVUCZ307G2k3/UhmA8PPGBoyuWaSw=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "2c15aa59df0017ca140d9ba302412298ab4bf22a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "home-manager": "home-manager",
         "iosevka-custom": "iosevka-custom",
         "nixpkgs": "nixpkgs_2",
-        "stylix": "stylix"
+        "stylix": "stylix",
+        "treefmt-nix": "treefmt-nix"
       }
     },
     "stylix": {
@@ -314,6 +331,24 @@
         "repo": "tinted-tmux",
         "type": "github"
       }
+    },
+    "treefmt-nix": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1733761991,
+        "narHash": "sha256-s4DalCDepD22jtKL5Nw6f4LP5UwoMcPzPZgHWjAfqbQ=",
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "rev": "0ce9d149d99bc383d1f2d85f31f6ebd146e46085",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "treefmt-nix",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index bcb0ecfb..76ccff3a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,6 +8,7 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-24.11";
+    treefmt-nix.url = "github:numtide/treefmt-nix";
     iosevka-custom.url = "git+https://git.xenia.me.uk/pixelifytica/iosevka.git";
     home-manager = {
       url = "github:nix-community/home-manager/release-24.11";
@@ -23,8 +24,18 @@
   };
 
   outputs =
-    inputs@{ nixpkgs, ... }:
+    inputs@{
+      self,
+      nixpkgs,
+      treefmt-nix,
+      ...
+    }:
+    let
+      treefmt = treefmt-nix.lib.evalModule nixpkgs.legacyPackages.x86_64-linux ./treefmt.nix;
+    in
     {
+      formatter.x86_64-linux = treefmt.config.build.wrapper;
+      checks.x86_64-linux.formatting = treefmt.config.build.check self;
       nixosConfigurations = {
         ## Server
         Legion = nixpkgs.lib.nixosSystem {
diff --git a/system/hardware-configuration/Monarch.nix b/system/hardware-configuration/Monarch.nix
index 14f1cd58..db2e917e 100644
--- a/system/hardware-configuration/Monarch.nix
+++ b/system/hardware-configuration/Monarch.nix
@@ -31,7 +31,8 @@
     fsType = "ext4";
   };
 
-  boot.initrd.luks.devices."luks-bf1eab3a-6d92-430d-a282-8dd4c9efe2c7".device = "/dev/disk/by-uuid/bf1eab3a-6d92-430d-a282-8dd4c9efe2c7";
+  boot.initrd.luks.devices."luks-bf1eab3a-6d92-430d-a282-8dd4c9efe2c7".device =
+    "/dev/disk/by-uuid/bf1eab3a-6d92-430d-a282-8dd4c9efe2c7";
 
   fileSystems."/boot" = {
     device = "/dev/disk/by-uuid/85D5-B6EC";
diff --git a/system/hardware-configuration/Northstar.nix b/system/hardware-configuration/Northstar.nix
index 2b46114e..741ae945 100644
--- a/system/hardware-configuration/Northstar.nix
+++ b/system/hardware-configuration/Northstar.nix
@@ -26,7 +26,8 @@
     fsType = "ext4";
   };
 
-  boot.initrd.luks.devices."luks-d1062931-ee58-4848-adf9-09452daeb6eb".device = "/dev/disk/by-uuid/d1062931-ee58-4848-adf9-09452daeb6eb";
+  boot.initrd.luks.devices."luks-d1062931-ee58-4848-adf9-09452daeb6eb".device =
+    "/dev/disk/by-uuid/d1062931-ee58-4848-adf9-09452daeb6eb";
 
   fileSystems."/boot" = {
     device = "/dev/disk/by-uuid/ABE3-88E7";
diff --git a/system/hardware-configuration/Tone.nix b/system/hardware-configuration/Tone.nix
index ee32fc32..2f1540d3 100644
--- a/system/hardware-configuration/Tone.nix
+++ b/system/hardware-configuration/Tone.nix
@@ -28,7 +28,8 @@
     fsType = "ext4";
   };
 
-  boot.initrd.luks.devices."luks-08822b9c-e9d6-424c-bc75-373f8667526d".device = "/dev/disk/by-uuid/08822b9c-e9d6-424c-bc75-373f8667526d";
+  boot.initrd.luks.devices."luks-08822b9c-e9d6-424c-bc75-373f8667526d".device =
+    "/dev/disk/by-uuid/08822b9c-e9d6-424c-bc75-373f8667526d";
 
   fileSystems."/boot/efi" = {
     device = "/dev/disk/by-uuid/6009-89FC";
diff --git a/system/hardware-configuration/Vanguard.nix b/system/hardware-configuration/Vanguard.nix
index a4c4b705..6c1c7a72 100644
--- a/system/hardware-configuration/Vanguard.nix
+++ b/system/hardware-configuration/Vanguard.nix
@@ -29,7 +29,8 @@
     fsType = "ext4";
   };
 
-  boot.initrd.luks.devices."luks-0d50df5f-9456-4296-9156-f5b818e11552".device = "/dev/disk/by-uuid/0d50df5f-9456-4296-9156-f5b818e11552";
+  boot.initrd.luks.devices."luks-0d50df5f-9456-4296-9156-f5b818e11552".device =
+    "/dev/disk/by-uuid/0d50df5f-9456-4296-9156-f5b818e11552";
 
   fileSystems."/boot" = {
     device = "/dev/disk/by-uuid/3297-A70D";
diff --git a/system/services/grafana.nix b/system/services/grafana.nix
index 98b9ec39..51b8f03c 100644
--- a/system/services/grafana.nix
+++ b/system/services/grafana.nix
@@ -32,5 +32,6 @@
       # }
     ];
   };
-  services.caddy.virtualHosts."grafana.xenia.me.uk".extraConfig = "reverse_proxy http://localhost:3000";
+  services.caddy.virtualHosts."grafana.xenia.me.uk".extraConfig =
+    "reverse_proxy http://localhost:3000";
 }
diff --git a/system/services/nix-serve.nix b/system/services/nix-serve.nix
index 5ba93de5..7cc633bd 100644
--- a/system/services/nix-serve.nix
+++ b/system/services/nix-serve.nix
@@ -6,5 +6,6 @@
     openFirewall = true;
     secretKeyFile = "/root/nix-serve.key";
   };
-  services.caddy.virtualHosts."nix.xenia.me.uk".extraConfig = "reverse_proxy http://localhost:${toString config.services.nix-serve.port}";
+  services.caddy.virtualHosts."nix.xenia.me.uk".extraConfig =
+    "reverse_proxy http://localhost:${toString config.services.nix-serve.port}";
 }
diff --git a/system/services/owncast.nix b/system/services/owncast.nix
index 924d9ac5..b2d1e270 100644
--- a/system/services/owncast.nix
+++ b/system/services/owncast.nix
@@ -6,5 +6,6 @@
     port = 9090;
     openFirewall = true;
   };
-  services.caddy.virtualHosts."stream.xenia.me.uk".extraConfig = "reverse_proxy http://localhost:${config.services.owncast.port}";
+  services.caddy.virtualHosts."stream.xenia.me.uk".extraConfig =
+    "reverse_proxy http://localhost:${config.services.owncast.port}";
 }
diff --git a/treefmt.nix b/treefmt.nix
new file mode 100644
index 00000000..970592a6
--- /dev/null
+++ b/treefmt.nix
@@ -0,0 +1,5 @@
+{ ... }:
+{
+  projectRootFile = "flake.nix";
+  programs.nixfmt.enable = true;
+}