diff --git a/handler/tool.go b/handler/tool.go
index c1f2d91..89604eb 100644
--- a/handler/tool.go
+++ b/handler/tool.go
@@ -240,6 +240,7 @@ func subscribeAndHandleMessagesV3(ws *websocket.Conn, deviceId int) {
 				}
 			}
 		}
+		buf = nil
 		time.Sleep(100 * time.Millisecond)
 		tCount++
 	}