diff --git a/src/quickfix.c b/src/quickfix.c
index 742a1ee..910c806 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -2603,6 +2603,8 @@
 
     if (wp != NULL)
     {
+	if (!win_valid(wp))
+	    return FALSE;
 	qi = GET_LOC_LIST(wp);	    // Location list
 	if (qi == NULL)
 	    return FALSE;