diff --git a/string_list_special.c b/string_list_special.c
index 15ca065a28..6d89e24930 100644
--- a/string_list_special.c
+++ b/string_list_special.c
@@ -235,7 +235,8 @@ struct string_list *string_list_new_special(enum string_list_type type,
 
 error:
    string_list_free(s);
-   s = NULL;
+   s    = NULL;
+   *len = 0;
    return NULL;
 }