diff --git a/treefmt.nix b/treefmt.nix
index e0195f0..65ba6fa 100644
--- a/treefmt.nix
+++ b/treefmt.nix
@@ -1,4 +1,4 @@
-{ ... }:
+{ pkgs, ... }:
 {
   projectRootFile = "flake.nix";
 
@@ -8,4 +8,12 @@
   programs.taplo.enable = true;
   programs.mdformat.enable = true;
   programs.shellcheck.enable = true;
+
+  settings.formatter = {
+    "kdlfmt" = {
+      command = "${pkgs.kdlfmt}/bin/kdlfmt";
+      options = [ "format" ];
+      includes = [ "*.kdl" ];
+    };
+  };
 }