diff --git a/cmd/gost/vendor/github.com/ginuerzh/gost/ss.go b/cmd/gost/vendor/github.com/ginuerzh/gost/ss.go
index 81d48af..3959ad2 100644
--- a/cmd/gost/vendor/github.com/ginuerzh/gost/ss.go
+++ b/cmd/gost/vendor/github.com/ginuerzh/gost/ss.go
@@ -283,7 +283,7 @@ func (s *ShadowUdpServer) ListenAndServe() error {
 			}
 
 			select {
-			case ch <- &packet{srcAddr: addr.String(), dstAddr: dgram.Header.Addr.String(), data: b[:n+3]}:
+			case ch <- &packet{srcAddr: addr.String(), dstAddr: dgram.Header.Addr.String(), data: dgram.Data}:
 			case <-time.After(time.Second * 3):
 				glog.V(LWARNING).Infof("[ssu] %s -> %s : %s", addr, dgram.Header.Addr.String(), "send queue is full, discard")
 			}
@@ -292,12 +292,26 @@ func (s *ShadowUdpServer) ListenAndServe() error {
 	// start recv queue
 	go func(ch <-chan *packet) {
 		for pkt := range ch {
+			srcAddr, err := net.ResolveUDPAddr("udp", pkt.srcAddr)
+			if err != nil {
+				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
+				continue
+			}
 			dstAddr, err := net.ResolveUDPAddr("udp", pkt.dstAddr)
 			if err != nil {
 				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
 				continue
 			}
-			if _, err := conn.WriteTo(pkt.data, dstAddr); err != nil {
+
+			dgram := gosocks5.NewUDPDatagram(gosocks5.NewUDPHeader(0, 0, ToSocksAddr(srcAddr)), pkt.data)
+			b := bytes.Buffer{}
+			dgram.Write(&b)
+			if b.Len() < 10 {
+				glog.V(LWARNING).Infof("[ssu] %s <- %s : invalid udp datagram", pkt.dstAddr, pkt.srcAddr)
+				continue
+			}
+
+			if _, err := conn.WriteTo(b.Bytes()[3:], dstAddr); err != nil { // remove rsv and frag fields to make it standard shadowsocks UDP datagram
 				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
 				return
 			}
diff --git a/cmd/gost/vendor/vendor.json b/cmd/gost/vendor/vendor.json
index 25bb639..58ba5da 100644
--- a/cmd/gost/vendor/vendor.json
+++ b/cmd/gost/vendor/vendor.json
@@ -21,10 +21,10 @@
 			"revisionTime": "2017-01-19T05:34:58Z"
 		},
 		{
-			"checksumSHA1": "idpL1fpHpfntk74IVfWtkP1PMZs=",
+			"checksumSHA1": "2kMuCJwcxppxWtk9dX1WtWZMGB4=",
 			"path": "github.com/ginuerzh/gost",
-			"revision": "321b03712af504981d35a47c50c2cfe4dd788a9d",
-			"revisionTime": "2017-01-21T03:16:33Z"
+			"revision": "8861ffba01779f3a9f44b205b38d626fce71dff3",
+			"revisionTime": "2017-01-24T13:01:52Z"
 		},
 		{
 			"checksumSHA1": "URsJa4y/sUUw/STmbeYx9EKqaYE=",
diff --git a/ss.go b/ss.go
index 81d48af..3959ad2 100644
--- a/ss.go
+++ b/ss.go
@@ -283,7 +283,7 @@ func (s *ShadowUdpServer) ListenAndServe() error {
 			}
 
 			select {
-			case ch <- &packet{srcAddr: addr.String(), dstAddr: dgram.Header.Addr.String(), data: b[:n+3]}:
+			case ch <- &packet{srcAddr: addr.String(), dstAddr: dgram.Header.Addr.String(), data: dgram.Data}:
 			case <-time.After(time.Second * 3):
 				glog.V(LWARNING).Infof("[ssu] %s -> %s : %s", addr, dgram.Header.Addr.String(), "send queue is full, discard")
 			}
@@ -292,12 +292,26 @@ func (s *ShadowUdpServer) ListenAndServe() error {
 	// start recv queue
 	go func(ch <-chan *packet) {
 		for pkt := range ch {
+			srcAddr, err := net.ResolveUDPAddr("udp", pkt.srcAddr)
+			if err != nil {
+				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
+				continue
+			}
 			dstAddr, err := net.ResolveUDPAddr("udp", pkt.dstAddr)
 			if err != nil {
 				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
 				continue
 			}
-			if _, err := conn.WriteTo(pkt.data, dstAddr); err != nil {
+
+			dgram := gosocks5.NewUDPDatagram(gosocks5.NewUDPHeader(0, 0, ToSocksAddr(srcAddr)), pkt.data)
+			b := bytes.Buffer{}
+			dgram.Write(&b)
+			if b.Len() < 10 {
+				glog.V(LWARNING).Infof("[ssu] %s <- %s : invalid udp datagram", pkt.dstAddr, pkt.srcAddr)
+				continue
+			}
+
+			if _, err := conn.WriteTo(b.Bytes()[3:], dstAddr); err != nil { // remove rsv and frag fields to make it standard shadowsocks UDP datagram
 				glog.V(LWARNING).Infof("[ssu] %s <- %s : %s", pkt.dstAddr, pkt.srcAddr, err)
 				return
 			}