diff --git a/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala b/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
index 44b2b8c0..fe5c7bc2 100644
--- a/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
+++ b/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
@@ -61,6 +61,8 @@ object TrafficMonitor {
     rxRate = 0
     txTotal = 0
     rxTotal = 0
+    txLast = 0
+    rxLast = 0
     last = getTraffic(0, 0)
   }