diff --git a/dlls/winex11.drv/winpos.c b/dlls/winex11.drv/winpos.c
index 0b10c145f5f..56c2b7c17cf 100644
--- a/dlls/winex11.drv/winpos.c
+++ b/dlls/winex11.drv/winpos.c
@@ -382,6 +382,7 @@ BOOL X11DRV_SetWindowPos( HWND hwnd, HWND insert_after, const RECT *rectWindow,
                     X11DRV_set_wm_hints( display, data );
                     wine_tsx11_lock();
                     XMapWindow( display, data->whole_window );
+                    XFlush( display );
                     wine_tsx11_unlock();
                     mapped = TRUE;
                 }
@@ -391,6 +392,7 @@ BOOL X11DRV_SetWindowPos( HWND hwnd, HWND insert_after, const RECT *rectWindow,
                     TRACE( "mapping non zero size or off-screen win %p\n", hwnd );
                     wine_tsx11_lock();
                     XMapWindow( display, data->whole_window );
+                    XFlush( display );
                     wine_tsx11_unlock();
                     mapped = TRUE;
                 }