1 files changed, 2 insertions, 2 deletions

diff --git a/src/xfns.c b/src/xfns.c
index fd691063ed5..da8ed3826dc 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -1206,8 +1206,8 @@ x_set_menu_bar_lines_1 (window, n)
 {
   struct window *w = XWINDOW (window);
 
-  XFASTINT (w->top) += n;
-  XFASTINT (w->height) -= n;
+  XSETFASTINT (w->top, XFASTINT (w->top) + n);
+  XSETFASTINT (w->height, XFASTINT (w->height) - n);
 
   /* Handle just the top child in a vertical split.  */
   if (!NILP (w->vchild))