diff --git a/dlls/user32/user_private.h b/dlls/user32/user_private.h
index 9e65e9f1f66..73f01871d8c 100644
--- a/dlls/user32/user_private.h
+++ b/dlls/user32/user_private.h
@@ -44,24 +44,6 @@
 
 struct window_surface;
 
-/* internal messages codes */
-enum wine_internal_message
-{
-    WM_WINE_DESTROYWINDOW = 0x80000000,
-    WM_WINE_SETWINDOWPOS,
-    WM_WINE_SHOWWINDOW,
-    WM_WINE_SETPARENT,
-    WM_WINE_SETWINDOWLONG,
-    WM_WINE_SETSTYLE,
-    WM_WINE_SETACTIVEWINDOW,
-    WM_WINE_KEYBOARD_LL_HOOK,
-    WM_WINE_MOUSE_LL_HOOK,
-    WM_WINE_CLIPCURSOR,
-    WM_WINE_UPDATEWINDOWSTATE,
-    WM_WINE_FIRST_DRIVER_MSG = 0x80001000,  /* range of messages reserved for the USER driver */
-    WM_WINE_LAST_DRIVER_MSG = 0x80001fff
-};
-
 extern const struct user_driver_funcs *USER_Driver DECLSPEC_HIDDEN;
 
 extern void USER_unload_driver(void) DECLSPEC_HIDDEN;
diff --git a/dlls/user32/win.c b/dlls/user32/win.c
index 02891cd34ce..4f860889024 100644
--- a/dlls/user32/win.c
+++ b/dlls/user32/win.c
@@ -1208,16 +1208,14 @@ static WND *next_thread_window( HWND *hwnd )
 void destroy_thread_windows(void)
 {
     WND *wndPtr;
-    HWND hwnd = 0, *list;
+    HWND hwnd = 0;
     HMENU menu, sys_menu;
     struct window_surface *surface;
-    int i;
 
     while ((wndPtr = next_thread_window( &hwnd )))
     {
         /* destroy the client-side storage */
 
-        list = WIN_ListChildren( hwnd );
         menu = ((wndPtr->dwStyle & (WS_CHILD | WS_POPUP)) != WS_CHILD) ? (HMENU)wndPtr->wIDmenu : 0;
         sys_menu = wndPtr->hSysMenu;
         free_dce( wndPtr->dce, hwnd );
@@ -1232,14 +1230,6 @@ void destroy_thread_windows(void)
             register_window_surface( surface, NULL );
             window_surface_release( surface );
         }
-
-        /* free child windows */
-
-        if (!list) continue;
-        for (i = 0; list[i]; i++)
-            if (!WIN_IsCurrentThread( list[i] ))
-                SendNotifyMessageW( list[i], WM_WINE_DESTROYWINDOW, 0, 0 );
-        HeapFree( GetProcessHeap(), 0, list );
     }
 }
 
diff --git a/include/ntuser.h b/include/ntuser.h
index a9dd8d2e3fd..4b665e6a364 100644
--- a/include/ntuser.h
+++ b/include/ntuser.h
@@ -102,6 +102,25 @@ struct user_thread_info
 
 C_ASSERT( sizeof(struct user_thread_info) <= sizeof(((TEB *)0)->Win32ClientInfo) );
 
+/* internal messages codes */
+enum wine_internal_message
+{
+    WM_WINE_DESTROYWINDOW = 0x80000000,
+    WM_WINE_SETWINDOWPOS,
+    WM_WINE_SHOWWINDOW,
+    WM_WINE_SETPARENT,
+    WM_WINE_SETWINDOWLONG,
+    WM_WINE_SETSTYLE,
+    WM_WINE_SETACTIVEWINDOW,
+    WM_WINE_KEYBOARD_LL_HOOK,
+    WM_WINE_MOUSE_LL_HOOK,
+    WM_WINE_CLIPCURSOR,
+    WM_WINE_UPDATEWINDOWSTATE,
+    WM_WINE_FIRST_DRIVER_MSG = 0x80001000,  /* range of messages reserved for the USER driver */
+    WM_WINE_LAST_DRIVER_MSG = 0x80001fff
+};
+
+
 HKL     WINAPI NtUserActivateKeyboardLayout( HKL layout, UINT flags );
 BOOL    WINAPI NtUserAddClipboardFormatListener( HWND hwnd );
 BOOL    WINAPI NtUserAttachThreadInput( DWORD from, DWORD to, BOOL attach );
diff --git a/server/window.c b/server/window.c
index 9fd67656eea..506f0269ee1 100644
--- a/server/window.c
+++ b/server/window.c
@@ -27,9 +27,7 @@
 #define WIN32_NO_STATUS
 #include "windef.h"
 #include "winbase.h"
-#include "wingdi.h"
-#include "winuser.h"
-#include "winternl.h"
+#include "ntuser.h"
 
 #include "object.h"
 #include "request.h"
@@ -1965,12 +1963,18 @@ void free_window_handle( struct window *win )
     LIST_FOR_EACH_ENTRY_SAFE( child, next, &win->children, struct window, entry )
     {
         if (!child->handle) continue;
-        free_window_handle( child );
+        if (!win->thread || !child->thread || win->thread == child->thread)
+            free_window_handle( child );
+        else
+            send_notify_message( child->handle, WM_WINE_DESTROYWINDOW, 0, 0 );
     }
     LIST_FOR_EACH_ENTRY_SAFE( child, next, &win->children, struct window, entry )
     {
         if (!child->handle) continue;
-        free_window_handle( child );
+        if (!win->thread || !child->thread || win->thread == child->thread)
+            free_window_handle( child );
+        else
+            send_notify_message( child->handle, WM_WINE_DESTROYWINDOW, 0, 0 );
     }
 
     /* reset global window pointers, if the corresponding window is destroyed */