diff --git a/flake.nix b/flake.nix
index 9c1a76a..96b46c9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -21,6 +21,12 @@
 
       defaultPackage = packages.youmubot;
 
+      overlays.default = final: prev: {
+        youmubot = final.callPackage ./package.nix {
+          naersk = final.callPackage inputs.naersk { };
+        };
+      };
+
       # `nix run`
       apps.youmubot = flake-utils.lib.mkApp {
         drv = packages.youmubot;
diff --git a/module.nix b/module.nix
index b8afb05..720f11a 100644
--- a/module.nix
+++ b/module.nix
@@ -7,6 +7,10 @@ in
 {
   options.services.youmubot = {
     enable = mkEnableOption "Enable youmubot, the discord bot made with Rust.";
+    package = mkOption {
+      type = types.package;
+      default = youmubot;
+    };
 
     envFile = mkOption {
       type = types.path;
@@ -35,7 +39,7 @@ in
       description = "the discord bot made with Rust";
       documentation = [ "https://github.com/natsukagami/youmubot" ];
 
-      script = "${youmubot}/bin/youmubot";
+      script = "${cfg.package}/bin/youmubot";
 
       environment = {
         DBPATH = cfg.databasePath;