diff --git a/src/mark.c b/src/mark.c
index 1ac91d8..9c17f7a 100644
--- a/src/mark.c
+++ b/src/mark.c
@@ -1374,7 +1374,8 @@
 set_last_cursor(win)
     win_T	*win;
 {
-    win->w_buffer->b_last_cursor = win->w_cursor;
+    if (win->w_buffer != NULL)
+	win->w_buffer->b_last_cursor = win->w_cursor;
 }
 
 #if defined(EXITFREE) || defined(PROTO)