diff --git a/src/client/src/tscSystem.c b/src/client/src/tscSystem.c
index fabe0df69be03b2dd817a1a8d56f9b2f07148f1f..7041c922d9b8ff32d6c1340fe313769cf4cf9729 100644
--- a/src/client/src/tscSystem.c
+++ b/src/client/src/tscSystem.c
@@ -113,7 +113,7 @@ int32_t tscAcquireRpc(const char *key, const char *user, const char *secretEncry
 
   SRpcObj rpcObj;
   memset(&rpcObj, 0, sizeof(rpcObj));
-  tstrncpy(rpcObj.key, key, strlen(key));
+  tstrncpy(rpcObj.key, key, sizeof(rpcObj.key));
   rpcObj.pDnodeConn = rpcOpen(&rpcInit);
   if (rpcObj.pDnodeConn == NULL) {
     pthread_mutex_unlock(&rpcObjMutex);