diff --git a/src/util/src/tskiplist.c b/src/util/src/tskiplist.c
index 20bec169546d6514def2453257346d5f94826187..7c950b7999b627d9334eae37eab35e1796c804dc 100644
--- a/src/util/src/tskiplist.c
+++ b/src/util/src/tskiplist.c
@@ -280,7 +280,10 @@ bool tSkipListIterNext(SSkipListIterator *iter) {
   tSkipListRLock(pSkipList);
 
   if (iter->order == TSDB_ORDER_ASC) {
-    if (iter->cur == pSkipList->pTail) return false;
+    if (iter->cur == pSkipList->pTail) {
+      tSkipListUnlock(pSkipList);
+      return false;
+    }
     iter->cur = SL_NODE_GET_FORWARD_POINTER(iter->cur, 0);
 
     // a new node is inserted into between iter->cur and iter->next, ignore it