diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 8be38be5048da9d5faab23deb565888e7319d639..0a018c863f2d6b456eb0ad1006bdc74971fb5e9c 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -8415,7 +8415,7 @@ static int32_t doValidateSubquery(SSqlNode* pSqlNode, int32_t index, SSqlObj* pS
       return invalidOperationMsg(msgBuf, "subquery alias name too long");
     }
 
-    tstrncpy(pTableMetaInfo1->aliasName, subInfo->aliasName.z, sizeof(pTableMetaInfo1->aliasName));
+    tstrncpy(pTableMetaInfo1->aliasName, subInfo->aliasName.z, subInfo->aliasName.n + 1);
   }
 
   taosArrayPush(pQueryInfo->pUpstream, &pSub);