diff --git a/source/libs/nodes/src/nodesCloneFuncs.c b/source/libs/nodes/src/nodesCloneFuncs.c
index 12cd6f1bc1..60692323f5 100644
--- a/source/libs/nodes/src/nodesCloneFuncs.c
+++ b/source/libs/nodes/src/nodesCloneFuncs.c
@@ -141,12 +141,12 @@ static SNode* valueNodeCopy(const SValueNode* pSrc, SValueNode* pDst) {
     case TSDB_DATA_TYPE_NCHAR:
     case TSDB_DATA_TYPE_VARCHAR:
     case TSDB_DATA_TYPE_VARBINARY:
-      pDst->datum.p = malloc(pSrc->node.resType.bytes + VARSTR_HEADER_SIZE);
+      pDst->datum.p = malloc(pSrc->node.resType.bytes + VARSTR_HEADER_SIZE + 1);
       if (NULL == pDst->datum.p) {
         nodesDestroyNode(pDst);
         return NULL;
       }
-      memcpy(pDst->datum.p, pSrc->datum.p, pSrc->node.resType.bytes + VARSTR_HEADER_SIZE);
+      memcpy(pDst->datum.p, pSrc->datum.p, pSrc->node.resType.bytes + VARSTR_HEADER_SIZE + 1);
       break;
     case TSDB_DATA_TYPE_JSON:
     case TSDB_DATA_TYPE_DECIMAL: