diff --git a/source/dnode/mnode/impl/src/mndShow.c b/source/dnode/mnode/impl/src/mndShow.c
index 029a1e6f8c5cb06f040432d8e8324a8afa14a3fd..164bcc7d60bc2caf51ad1dc7f9bb60e6c99b8ee9 100644
--- a/source/dnode/mnode/impl/src/mndShow.c
+++ b/source/dnode/mnode/impl/src/mndShow.c
@@ -234,7 +234,7 @@ static int32_t mndProcessRetrieveSysTableReq(SRpcMsg *pReq) {
   if (retrieveReq.user[0] != 0) {
     memcpy(pReq->info.conn.user, retrieveReq.user, TSDB_USER_LEN);
   } else {
-    memcpy(pReq->info.conn.user, TSDB_DEFAULT_USER, TSDB_USER_LEN);
+    memcpy(pReq->info.conn.user, TSDB_DEFAULT_USER, strlen(TSDB_DEFAULT_USER) + 1);
   }
   if (mndCheckShowPrivilege(pMnode, pReq->info.conn.user, pShow->type, retrieveReq.db) != 0) {
     return -1;