diff --git a/string-list.c b/string-list.c
index 9b023a258..51681189e 100644
--- a/string-list.c
+++ b/string-list.c
@@ -153,6 +153,7 @@ struct string_list_item *string_list_append(struct string_list *list, const char
 	ALLOC_GROW(list->items, list->nr + 1, list->alloc);
 	list->items[list->nr].string =
 		list->strdup_strings ? xstrdup(string) : (char *)string;
+	list->items[list->nr].util = NULL;
 	return list->items + list->nr++;
 }