diff --git a/src/eval.c b/src/eval.c
index 840e1e8..5c584de 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2951,7 +2951,7 @@
 	/*
 	 * Check whether any of the list items is locked
 	 */
-	for (ri = rettv->vval.v_list->lv_first; ri != NULL; )
+	for (ri = rettv->vval.v_list->lv_first; ri != NULL && ll_li != NULL; )
 	{
 	    if (tv_check_lock(ll_li->li_tv.v_lock, lp->ll_name))
 		return;