diff --git a/cmd/chihaya-e2e/main.go b/cmd/chihaya-e2e/main.go
index f59ed64..474c446 100644
--- a/cmd/chihaya-e2e/main.go
+++ b/cmd/chihaya-e2e/main.go
@@ -15,8 +15,8 @@ import (
 )
 
 func init() {
-	flag.StringVar(&httpTrackerURL, "http", "http://localhost:6969/announce", "the address of the HTTP tracker")
-	flag.StringVar(&udpTrackerURL, "udp", "udp://localhost:6969", "the address of the UDP tracker")
+	flag.StringVar(&httpTrackerURL, "http", "http://127.0.0.1:6969/announce", "the address of the HTTP tracker")
+	flag.StringVar(&udpTrackerURL, "udp", "udp://127.0.0.1:6969", "the address of the UDP tracker")
 	flag.DurationVar(&delay, "delay", 1*time.Second, "the delay between announces")
 }