diff --git a/dlls/user/painting.c b/dlls/user/painting.c
index ff9b309f062..0bd84b07f97 100644
--- a/dlls/user/painting.c
+++ b/dlls/user/painting.c
@@ -354,6 +354,7 @@ static void update_now( HWND hwnd, UINT rdw_flags )
                 send_erase( child, erase_flags, hrgn, &rect, NULL );
                 DeleteObject( hrgn );
             }
+            prev = 0;
         }
         else
         {