diff --git a/dlls/user32/tests/win.c b/dlls/user32/tests/win.c
index aba93598cc3..a858f6bac7a 100644
--- a/dlls/user32/tests/win.c
+++ b/dlls/user32/tests/win.c
@@ -7533,6 +7533,170 @@ static void test_window_without_child_style(void)
     DestroyWindow(hwnd);
 }
 
+
+struct smresult_thread_data
+{
+    HWND main_hwnd;
+    HWND thread_hwnd;
+    HANDLE thread_started;
+    HANDLE thread_got_wm_app;
+    HANDLE main_in_wm_app_1;
+    HANDLE thread_replied;
+};
+
+
+static LRESULT WINAPI smresult_wndproc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
+{
+    switch (msg)
+    {
+    case WM_APP:
+    {
+        struct smresult_thread_data *data = (struct smresult_thread_data*)lparam;
+
+        ok(hwnd == data->thread_hwnd, "unexpected hwnd %p\n", hwnd);
+
+        SendNotifyMessageA(data->main_hwnd, WM_APP+1, 0, lparam);
+
+        /* Don't return until the main thread is processing our sent message. */
+        ok(WaitForSingleObject(data->main_in_wm_app_1, INFINITE) == WAIT_OBJECT_0, "WaitForSingleObject failed\n");
+
+        /* Break the PeekMessage loop so we can notify the main thread after we return. */
+        SetEvent(data->thread_got_wm_app);
+
+        return 0x240408ea;
+    }
+    case WM_APP+1:
+    {
+        struct smresult_thread_data *data = (struct smresult_thread_data*)lparam;
+        LRESULT res;
+
+        ok(hwnd == data->main_hwnd, "unexpected hwnd %p\n", hwnd);
+
+        /* Ask the thread to reply to our WM_APP message. */
+        SetEvent(data->main_in_wm_app_1);
+
+        /* Wait until the thread has sent a reply. */
+        ok(WaitForSingleObject(data->thread_replied, INFINITE) == WAIT_OBJECT_0, "WaitForSingleObject failed\n");
+
+        /* Send another message while we have a reply queued for the current one. */
+        res = SendMessageA(data->thread_hwnd, WM_APP+2, 0, lparam);
+        todo_wine ok(res == 0x449b0190, "unexpected result %lx\n", res);
+
+        return 0;
+    }
+    case WM_APP+2:
+    {
+        struct smresult_thread_data *data = (struct smresult_thread_data*)lparam;
+
+        ok(hwnd == data->thread_hwnd, "unexpected hwnd %p\n", hwnd);
+
+        /* Don't return until we know the main thread is processing sent messages. */
+        SendMessageA(data->main_hwnd, WM_NULL, 0, 0);
+
+        return 0x449b0190;
+    }
+    case WM_CLOSE:
+        PostQuitMessage(0);
+        break;
+    }
+    return DefWindowProcA(hwnd, msg, wparam, lparam);
+}
+
+static DWORD WINAPI smresult_thread_proc(void *param)
+{
+    MSG msg;
+    struct smresult_thread_data *data = param;
+
+    data->thread_hwnd = CreateWindowExA(0, "SmresultClass", "window caption text", WS_OVERLAPPEDWINDOW,
+                                      100, 100, 200, 200, 0, 0, 0, NULL);
+    ok(data->thread_hwnd != 0, "Failed to create overlapped window\n");
+
+    SetEvent(data->thread_started);
+
+    /* Loop until we've processed WM_APP. */
+    while (WaitForSingleObject(data->thread_got_wm_app, 0) != WAIT_OBJECT_0)
+    {
+        if (PeekMessageA(&msg, 0, 0, 0, PM_REMOVE))
+        {
+            TranslateMessage(&msg);
+            DispatchMessageA(&msg);
+        }
+        else
+        {
+            MsgWaitForMultipleObjects(1, &data->thread_got_wm_app, FALSE, INFINITE, QS_SENDMESSAGE);
+        }
+    }
+
+    /* Notify the main thread that we replied to its WM_APP message. */
+    SetEvent(data->thread_replied);
+
+    while (GetMessageA(&msg, 0, 0, 0))
+    {
+        TranslateMessage(&msg);
+        DispatchMessageA(&msg);
+    }
+
+    return 0;
+}
+
+static void test_smresult(void)
+{
+    WNDCLASSA cls;
+    HANDLE hThread;
+    DWORD tid;
+    struct smresult_thread_data data;
+    BOOL ret;
+    LRESULT res;
+
+    cls.style = CS_DBLCLKS;
+    cls.lpfnWndProc = smresult_wndproc;
+    cls.cbClsExtra = 0;
+    cls.cbWndExtra = 0;
+    cls.hInstance = GetModuleHandleA(0);
+    cls.hIcon = 0;
+    cls.hCursor = LoadCursorA(0, (LPCSTR)IDC_ARROW);
+    cls.hbrBackground = GetStockObject(WHITE_BRUSH);
+    cls.lpszMenuName = NULL;
+    cls.lpszClassName = "SmresultClass";
+
+    ret = RegisterClassA(&cls);
+    ok(ret, "RegisterClassA failed\n");
+
+    data.thread_started = CreateEventA(NULL, TRUE, FALSE, NULL);
+    ok(data.thread_started != NULL, "CreateEventA failed\n");
+
+    data.thread_got_wm_app = CreateEventA(NULL, TRUE, FALSE, NULL);
+    ok(data.thread_got_wm_app != NULL, "CreateEventA failed\n");
+
+    data.main_in_wm_app_1 = CreateEventA(NULL, TRUE, FALSE, NULL);
+    ok(data.main_in_wm_app_1 != NULL, "CreateEventA failed\n");
+
+    data.thread_replied = CreateEventA(NULL, TRUE, FALSE, NULL);
+    ok(data.thread_replied != NULL, "CreateEventA failed\n");
+
+    data.main_hwnd = CreateWindowExA(0, "SmresultClass", "window caption text", WS_OVERLAPPEDWINDOW,
+                                      100, 100, 200, 200, 0, 0, 0, NULL);
+
+    hThread = CreateThread(NULL, 0, smresult_thread_proc, &data, 0, &tid);
+    ok(hThread != NULL, "CreateThread failed, error %d\n", GetLastError());
+
+    ok(WaitForSingleObject(data.thread_started, INFINITE) == WAIT_OBJECT_0, "WaitForSingleObject failed\n");
+
+    res = SendMessageA(data.thread_hwnd, WM_APP, 0, (LPARAM)&data);
+    ok(res == 0x240408ea, "unexpected result %lx\n", res);
+
+    SendMessageA(data.thread_hwnd, WM_CLOSE, 0, 0);
+
+    DestroyWindow(data.main_hwnd);
+
+    ok(WaitForSingleObject(hThread, INFINITE) == WAIT_OBJECT_0, "WaitForSingleObject failed\n");
+
+    CloseHandle(data.thread_started);
+    CloseHandle(data.thread_got_wm_app);
+    CloseHandle(data.main_in_wm_app_1);
+    CloseHandle(data.thread_replied);
+}
+
 START_TEST(win)
 {
     HMODULE user32 = GetModuleHandleA( "user32.dll" );
@@ -7664,6 +7828,7 @@ START_TEST(win)
     test_map_points();
     test_update_region();
     test_window_without_child_style();
+    test_smresult();
 
     /* add the tests above this line */
     if (hhook) UnhookWindowsHookEx(hhook);