diff --git a/source/gui/detail/window_manager.cpp b/source/gui/detail/window_manager.cpp
index 7ba67d3e..affd3abd 100644
--- a/source/gui/detail/window_manager.cpp
+++ b/source/gui/detail/window_manager.cpp
@@ -1417,7 +1417,8 @@ namespace detail
 
 		void window_manager::remove_trash_handle(unsigned tid)
 		{
-			internal_scope_guard lock;
+			//Thread-Safe Required!
+			std::lock_guard<mutex_type> lock(mutex_);
 			impl_->wd_register.delete_trash(tid);
 		}