diff --git a/queue.h b/queue.h
index bbea8ec4d..df3733c6b 100644
--- a/queue.h
+++ b/queue.h
@@ -207,6 +207,8 @@ void q_sort(struct list_head *head, bool descend);
  *
  * No effect if queue is NULL or empty. If there has only one element, do
  * nothing.
+ * The memory allocated to nodes that are removed must be freed after their
+ * removal.
  *
  * Reference:
  * https://leetcode.com/problems/remove-nodes-from-linked-list/
@@ -222,6 +224,8 @@ int q_ascend(struct list_head *head);
  *
  * No effect if queue is NULL or empty. If there has only one element, do
  * nothing.
+ * The memory allocated to nodes that are removed must be freed after their
+ * removal.
  *
  * Reference:
  * https://leetcode.com/problems/remove-nodes-from-linked-list/