diff --git a/src/client/src/tscSystem.c b/src/client/src/tscSystem.c
index a3a582f8dda575fdba0f85dbf7eaa9e6ebd0301c..5134aa512cfe3ea10bdb06ce0548e977e809baa5 100644
--- a/src/client/src/tscSystem.c
+++ b/src/client/src/tscSystem.c
@@ -133,7 +133,7 @@ void tscClusterInfoDestroy(SClusterInfo *pObj) {
 void *tscAcquireClusterInfo(const char *clusterId) {
   pthread_mutex_lock(&clusterMutex);
   
-  int32_t len = strlen(clusterId);
+  size_t len = strlen(clusterId);
   SClusterInfo *pObj   = NULL;
   SClusterInfo **ppObj = taosHashGet(tscClusterMap, clusterId, len); 
   if (ppObj == NULL || *ppObj == NULL) {