diff --git a/fmt.nix b/fmt.nix
new file mode 100644
index 0000000..6a9888b
--- /dev/null
+++ b/fmt.nix
@@ -0,0 +1,37 @@
+{ inputs, ... }:
+{
+  imports = [ inputs.treefmt-nix.flakeModule ];
+  perSystem =
+    { ... }:
+    {
+      treefmt = {
+        projectRootFile = "flake.nix";
+        programs = {
+          nixfmt.enable = true;
+          prettier.enable = true;
+          yamlfmt.enable = true;
+          shfmt.enable = true;
+        };
+        settings = {
+          on-unmatched = "fatal";
+          global.excludes = [
+            "sops/*"
+            "vars/*"
+            "*/sops/*"
+            "*/vars/*"
+
+            "*/.gitignore"
+            "LICENSE"
+
+            "inventory.json"
+            "*.tfvars.sops.json"
+            "*nixos-vars.json"
+            "secrets.yaml"
+            "facter.json"
+            "secrets.auto.tfvars.sops.json"
+            "emu-files/*"
+          ];
+        };
+      };
+    };
+}