diff --git a/gral_windows.cpp b/gral_windows.cpp
index 4fd717b..38e9409 100644
--- a/gral_windows.cpp
+++ b/gral_windows.cpp
@@ -1059,8 +1059,26 @@ void gral_window_clipboard_paste(gral_window *window, void (*callback)(char cons
 	CloseClipboard();
 }
 
-void gral_window_run_on_main_thread(struct gral_window *window, void (*callback)(void *user_data), void *user_data) {
-	PostMessage((HWND)window, WM_USER, (WPARAM)callback, (LPARAM)user_data);
+struct MainThreadCallbackData {
+	void (*callback)(void *user_data);
+	void *user_data;
+};
+
+static void CALLBACK main_thread_completion_routine(ULONG_PTR parameter) {
+	MainThreadCallbackData *callback_data = (MainThreadCallbackData *)parameter;
+	callback_data->callback(callback_data->user_data);
+}
+
+void gral_window_run_on_main_thread(gral_window *window, void (*callback)(void *user_data), void *user_data) {
+	//PostMessage((HWND)window, WM_USER, (WPARAM)callback, (LPARAM)user_data);
+	MainThreadCallbackData *callback_data = new MainThreadCallbackData();
+	callback_data->callback = callback;
+	callback_data->user_data = user_data;
+	DWORD thread_id;
+	GetWindowThreadProcessId((HWND)window, &thread_id);
+	HANDLE thread = OpenThread(0, FALSE, thread_id);
+	QueueUserAPC(&main_thread_completion_routine, thread, (ULONG_PTR)callback_data);
+	CloseHandle(thread);
 }
 
 static void CALLBACK timer_completion_routine(LPVOID lpArgToCompletionRoutine, DWORD dwTimerLowValue, DWORD dwTimerHighValue) {