diff --git a/protocol/etch/engine.go b/protocol/etch/engine.go
index 876f3b8..6050f42 100644
--- a/protocol/etch/engine.go
+++ b/protocol/etch/engine.go
@@ -8,6 +8,13 @@ import (
 	"github.com/mohanson/daze/lib/doa"
 )
 
+// Conf is acting as package level configuration.
+var Conf = struct {
+	PayloadSize int
+}{
+	PayloadSize: 508,
+}
+
 // Server implemented the etch protocol.
 type Server struct {
 	Closer io.Closer
@@ -36,7 +43,7 @@ func (s *Server) Run() error {
 	log.Println("main: listen and serve on", s.Listen)
 
 	go func() {
-		buf := make([]byte, 512)
+		buf := make([]byte, Conf.PayloadSize)
 		for {
 			n, addr, err := conn.ReadFromUDP(buf)
 			if err != nil {