diff --git a/gui/libui/include/ui/App.h b/gui/libui/include/ui/App.h
index 8a0d45e0..ce1e2496 100644
--- a/gui/libui/include/ui/App.h
+++ b/gui/libui/include/ui/App.h
@@ -61,6 +61,7 @@ namespace ui
         HashMap<int, OwnedPtr<Window>> m_windows;
         bool m_should_close { false };
         os::EventLoop m_loop;
+        Vector<int> m_window_clear_queue;
 
         bool process_events();
 
diff --git a/gui/libui/include/ui/Window.h b/gui/libui/include/ui/Window.h
index 83d4f00f..ef6d4025 100644
--- a/gui/libui/include/ui/Window.h
+++ b/gui/libui/include/ui/Window.h
@@ -80,6 +80,12 @@ namespace ui
             return m_id;
         }
 
+        void on_close(os::Action&& action)
+        {
+            m_on_close_action = move(action);
+            m_has_on_close_action = true;
+        }
+
         ~Window();
 
       private:
@@ -93,6 +99,9 @@ namespace ui
         Option<int> m_old_mouse_buttons;
         bool m_decorated { false };
 
+        os::Action m_on_close_action;
+        bool m_has_on_close_action { false };
+
         struct ShortcutAction
         {
             bool intercept;
diff --git a/gui/libui/src/App.cpp b/gui/libui/src/App.cpp
index ee2717c6..d53b17b7 100644
--- a/gui/libui/src/App.cpp
+++ b/gui/libui/src/App.cpp
@@ -75,7 +75,7 @@ namespace ui
     void App::unregister_window(Window* window, Badge<Window>)
     {
         int id = window->id();
-        check(m_windows.try_remove(id));
+        m_window_clear_queue.try_append(id);
     }
 
     Window* App::find_window(int id)
@@ -124,6 +124,15 @@ namespace ui
     {
         check(m_main_window);
         m_client->check_for_messages().release_value();
+        for (int id : m_window_clear_queue)
+        {
+            check(m_windows.try_remove(id));
+
+            ui::CloseWindowRequest request;
+            request.window = id;
+            client().send_async(request);
+        }
+        m_window_clear_queue.clear_data();
         return !m_should_close;
     }
 }
diff --git a/gui/libui/src/Window.cpp b/gui/libui/src/Window.cpp
index 44f240dd..3aa699c6 100644
--- a/gui/libui/src/Window.cpp
+++ b/gui/libui/src/Window.cpp
@@ -84,6 +84,8 @@ namespace ui
     Window::~Window()
     {
         if (m_canvas.ptr) munmap(m_canvas.ptr, ((usize)m_canvas.width) * ((usize)m_canvas.height) * 4);
+
+        if (m_has_on_close_action) m_on_close_action();
     }
 
     void Window::set_title(StringView title)
@@ -108,10 +110,6 @@ namespace ui
     {
         App& app = App::the();
 
-        ui::CloseWindowRequest request;
-        request.window = m_id;
-        app.client().send_async(request);
-
         if (this == app.main_window()) app.set_should_close(true);
 
         app.unregister_window(this, {});