diff --git a/source/dnode/mnode/impl/src/mndStb.c b/source/dnode/mnode/impl/src/mndStb.c
index 5516b9d653..16825d73b1 100644
--- a/source/dnode/mnode/impl/src/mndStb.c
+++ b/source/dnode/mnode/impl/src/mndStb.c
@@ -861,7 +861,7 @@ int32_t mndBuildStbFromReq(SMnode *pMnode, SStbObj *pDst, SMCreateStbReq *pCreat
 static int32_t mndGenIdxNameForFirstTag(char *fullname, char *dbname, char *stbname, char *tagname) {
   SName name = {0};
   tNameFromString(&name, stbname, T_NAME_ACCT | T_NAME_DB | T_NAME_TABLE);
-  return snprintf(fullname, TSDB_INDEX_FNAME_LEN - 1, "%s.%s_%s", dbname, tagname, tNameGetTableName(&name));
+  return snprintf(fullname, TSDB_INDEX_FNAME_LEN, "%s.%s_%s", dbname, tagname, tNameGetTableName(&name));
 }
 
 static int32_t mndCreateStb(SMnode *pMnode, SRpcMsg *pReq, SMCreateStbReq *pCreate, SDbObj *pDb) {