diff --git a/buffet/manager.h b/buffet/manager.h
index 73ed8aa..ba7190d 100644
--- a/buffet/manager.h
+++ b/buffet/manager.h
@@ -59,7 +59,8 @@
   void HandleUpdateState(chromeos::ErrorPtr* error,
                          const std::string& json_state_fragment);
   // Handles calls to org.chromium.Buffet.Manager.Test()
-  void HandleTestMethod(chromeos::ErrorPtr* error);
+  std::string HandleTestMethod(chromeos::ErrorPtr* error,
+                               const std::string& message);
 
   chromeos::dbus_utils::DBusObject dbus_object_;