diff --git a/src/quickfix.c b/src/quickfix.c
index aa431ea..a3d3e8f 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -4492,7 +4492,7 @@
     // set to NULL.
     // A window displaying a location list buffer will have the w_llist_ref
     // pointing to the location list.
-    if (bt_quickfix(win->w_buffer))
+    if (buf_valid(win->w_buffer) && bt_quickfix(win->w_buffer))
 	if ((IS_QF_STACK(qi) && win->w_llist_ref == NULL)
 		|| (IS_LL_STACK(qi) && win->w_llist_ref == qi))
 	    return TRUE;