diff --git a/sess.go b/sess.go
index 7bce126..0b8bdf2 100644
--- a/sess.go
+++ b/sess.go
@@ -126,7 +126,7 @@ type (
 )
 
 // newUDPSession create a new udp session for client or server
-func newUDPSession(conv uint32, dataShards, parityShards int, l *Listener, conn net.PacketConn, ownConn bool, remote net.Addr, block BlockCrypt) *UDPSession {
+func newUDPSession(conv uint32, dataShards, parityShards int, remoteDataShards, remoteParityShards int, l *Listener, conn net.PacketConn, ownConn bool, remote net.Addr, block BlockCrypt) *UDPSession {
 	sess := new(UDPSession)
 	sess.die = make(chan struct{})
 	sess.nonce = new(nonceAES128)
@@ -155,7 +155,7 @@ func newUDPSession(conv uint32, dataShards, parityShards int, l *Listener, conn
 	}
 
 	// FEC codec initialization
-	sess.fecDecoder = newFECDecoder(rxFECMulti*(dataShards+parityShards), dataShards, parityShards)
+	sess.fecDecoder = newFECDecoder(rxFECMulti*(remoteDataShards+remoteParityShards), remoteDataShards, remoteParityShards)
 	if sess.block != nil {
 		sess.fecEncoder = newFECEncoder(dataShards, parityShards, cryptHeaderSize)
 	} else {
@@ -768,12 +768,14 @@ func (s *UDPSession) kcpInput(data []byte) {
 type (
 	// Listener defines a server which will be waiting to accept incoming connections
 	Listener struct {
-		block        BlockCrypt     // block encryption
-		dataShards   int            // FEC data shard
-		parityShards int            // FEC parity shard
-		fecDecoder   *fecDecoder    // FEC mock initialization
-		conn         net.PacketConn // the underlying packet connection
-		ownConn      bool           // true if we created conn internally, false if provided by caller
+		block              BlockCrypt     // block encryption
+		dataShards         int            // FEC data shard
+		parityShards       int            // FEC parity shard
+		remoteDataShards   int            // FEC remote data shard
+		remoteParityShards int            // FEC remote parity shard
+		fecDecoder         *fecDecoder    // FEC mock initialization
+		conn               net.PacketConn // the underlying packet connection
+		ownConn            bool           // true if we created conn internally, false if provided by caller
 
 		sessions        map[string]*UDPSession // all sessions accepted by this Listener
 		sessionLock     sync.Mutex
@@ -841,7 +843,7 @@ func (l *Listener) packetInput(data []byte, addr net.Addr) {
 
 		if s == nil && convValid { // new session
 			if len(l.chAccepts) < cap(l.chAccepts) { // do not let the new sessions overwhelm accept queue
-				s := newUDPSession(conv, l.dataShards, l.parityShards, l, l.conn, false, addr, l.block)
+				s := newUDPSession(conv, l.dataShards, l.parityShards, l.remoteDataShards, l.remoteParityShards, l, l.conn, false, addr, l.block)
 				s.kcpInput(data)
 				l.sessionLock.Lock()
 				l.sessions[addr.String()] = s
@@ -1001,15 +1003,15 @@ func ListenWithOptions(laddr string, block BlockCrypt, dataShards, parityShards
 		return nil, errors.WithStack(err)
 	}
 
-	return serveConn(block, dataShards, parityShards, conn, true)
+	return serveConn(block, dataShards, parityShards, dataShards, parityShards, conn, true)
 }
 
 // ServeConn serves KCP protocol for a single packet connection.
 func ServeConn(block BlockCrypt, dataShards, parityShards int, conn net.PacketConn) (*Listener, error) {
-	return serveConn(block, dataShards, parityShards, conn, false)
+	return serveConn(block, dataShards, parityShards, dataShards, parityShards, conn, false)
 }
 
-func serveConn(block BlockCrypt, dataShards, parityShards int, conn net.PacketConn, ownConn bool) (*Listener, error) {
+func serveConn(block BlockCrypt, dataShards, parityShards int, remoteDataShards, remoteParityShards int, conn net.PacketConn, ownConn bool) (*Listener, error) {
 	l := new(Listener)
 	l.conn = conn
 	l.ownConn = ownConn
@@ -1019,8 +1021,10 @@ func serveConn(block BlockCrypt, dataShards, parityShards int, conn net.PacketCo
 	l.die = make(chan struct{})
 	l.dataShards = dataShards
 	l.parityShards = parityShards
+	l.remoteDataShards = remoteDataShards
+	l.remoteParityShards = remoteParityShards
 	l.block = block
-	l.fecDecoder = newFECDecoder(rxFECMulti*(dataShards+parityShards), dataShards, parityShards)
+	l.fecDecoder = newFECDecoder(rxFECMulti*(remoteDataShards+remoteParityShards), remoteDataShards, remoteParityShards)
 	l.chSocketReadError = make(chan struct{})
 
 	// calculate header size
@@ -1063,12 +1067,12 @@ func DialWithOptions(raddr string, block BlockCrypt, dataShards, parityShards in
 
 	var convid uint32
 	binary.Read(rand.Reader, binary.LittleEndian, &convid)
-	return newUDPSession(convid, dataShards, parityShards, nil, conn, true, udpaddr, block), nil
+	return newUDPSession(convid, dataShards, parityShards, dataShards, parityShards, nil, conn, true, udpaddr, block), nil
 }
 
 // NewConn3 establishes a session and talks KCP protocol over a packet connection.
 func NewConn3(convid uint32, raddr net.Addr, block BlockCrypt, dataShards, parityShards int, conn net.PacketConn) (*UDPSession, error) {
-	return newUDPSession(convid, dataShards, parityShards, nil, conn, false, raddr, block), nil
+	return newUDPSession(convid, dataShards, parityShards, dataShards, parityShards, nil, conn, false, raddr, block), nil
 }
 
 // NewConn2 establishes a session and talks KCP protocol over a packet connection.