diff --git a/relay.go b/relay.go
index 9f3a30d..94699cb 100644
--- a/relay.go
+++ b/relay.go
@@ -334,16 +334,18 @@ func (c *relayConn) Write(b []byte) (n int, err error) {
 	if !c.udp {
 		return c.Conn.Write(b)
 	}
+
+	nsize := 2 + len(b)
 	var buf []byte
-	if 2+len(b) <= mediumBufferSize {
+	if nsize <= mediumBufferSize {
 		buf = mPool.Get().([]byte)
 		defer mPool.Put(buf)
 	} else {
-		buf = make([]byte, 2+len(b))
+		buf = make([]byte, nsize)
 	}
 	binary.BigEndian.PutUint16(buf[:2], uint16(len(b)))
 	n = copy(buf[2:], b)
-	_, err = c.Conn.Write(buf)
+	_, err = c.Conn.Write(buf[:nsize])
 	return
 }
 
diff --git a/tuntap.go b/tuntap.go
index 03feb4d..24bed37 100644
--- a/tuntap.go
+++ b/tuntap.go
@@ -336,7 +336,7 @@ func (h *tunHandler) transportTun(tun net.Conn, conn net.PacketConn, raddr net.A
 		for {
 			err := func() error {
 				b := sPool.Get().([]byte)
-				defer mPool.Put(b)
+				defer sPool.Put(b)
 
 				n, addr, err := conn.ReadFrom(b)
 				if err != nil &&
@@ -698,7 +698,7 @@ func (h *tapHandler) transportTap(tap net.Conn, conn net.PacketConn, raddr net.A
 		for {
 			err := func() error {
 				b := sPool.Get().([]byte)
-				defer mPool.Put(b)
+				defer sPool.Put(b)
 
 				n, addr, err := conn.ReadFrom(b)
 				if err != nil &&