diff --git a/flake.nix b/flake.nix
index 4afb27a..79c54f8 100644
--- a/flake.nix
+++ b/flake.nix
@@ -44,9 +44,22 @@
           ./machines
           ./routers
           ./inventories
+          ./overlays
           ./modules/clan/flake-module.nix
           ./modules/nixos/flake-module.nix
         ];
+        perSystem =
+          { pkgs, system, ... }:
+          {
+            _module.args.pkgs = import inputs.nixpkgs {
+              inherit system;
+              overlays = [
+                inputs.self.overlays.packagesOverlay
+              ];
+              config = { };
+            };
+            packages.default = pkgs.think-gtcm;
+          };
       }
     );
 }
diff --git a/overlays/default.nix b/overlays/default.nix
index f3d631e..583c8e9 100644
--- a/overlays/default.nix
+++ b/overlays/default.nix
@@ -1,6 +1,6 @@
 { ... }:
 {
   flake.overlays = {
-    packagesOverlay = ../pkgs/overlay.nix;
+    packagesOverlay = import ../pkgs/overlay.nix;
   };
 }
diff --git a/pkgs/think-gtcm.nix b/pkgs/think-gtcm.nix
index 43ca9f4..5a3e5ed 100644
--- a/pkgs/think-gtcm.nix
+++ b/pkgs/think-gtcm.nix
@@ -1,17 +1,31 @@
 {
   fetchurl,
+  fetchgit,
   php,
+  breakpointHook,
 }:
 php.buildComposerProject2 (finalAttrs: rec {
   pname = "think-gtcm";
   version = "1.0.0";
 
-  src = fetchurl {
+  src = fetchgit {
     url = "https://git.b4l.co.th/newedge/think-greaterchiangmai";
-    sha256 = "";
+    rev = "7c17aa78436538241c09fc7d633904d3c063011e";
+    hash = "sha256-GDx0+PmuCXC+UPtsvsocCZQiTPcnOZEzJI17sxrVv7Q=";
   };
 
-  composerLock = "${src}/think.greaterchiangmai.com/composer.lock";
+  unpackPhase = ''
+    runHook preUnpack
+
+    mkdir "$sourceRoot"
+
+    cp -R "$src/think.greaterchiangmai.com/*" "$sourceRoot/"
+
+    runHook postUnpack
+  '';
+
+  nativeBuildInputs = [ breakpointHook ];
+
   composerStrictValidation = false;
   vendorHash = "";
 
diff --git a/routers/default.nix b/routers/default.nix
index 0c5d3c5..cb37001 100644
--- a/routers/default.nix
+++ b/routers/default.nix
@@ -1,4 +1,4 @@
-{ inputs, ... }:
+{ inputs, pkgs, ... }:
 {
   flake.legacyPackages = {
     whitehouse-router = import "${inputs.liminix}/default.nix" {