diff --git a/internal/multiplex/session.go b/internal/multiplex/session.go
index 3a6df78..49572cc 100644
--- a/internal/multiplex/session.go
+++ b/internal/multiplex/session.go
@@ -154,10 +154,11 @@ func (sesh *Session) closeStream(s *Stream, active bool) error {
 		padding := genRandomPadding()
 		f := &Frame{
 			StreamID: s.id,
-			Seq:      atomic.AddUint64(&s.nextSendSeq, 1) - 1,
+			Seq:      s.nextSendSeq,
 			Closing:  C_STREAM,
 			Payload:  padding,
 		}
+		s.nextSendSeq++
 
 		obfsBuf := make([]byte, len(padding)+64)
 		i, err := sesh.Obfs(f, obfsBuf)
@@ -168,7 +169,7 @@ func (sesh *Session) closeStream(s *Stream, active bool) error {
 		if err != nil {
 			return err
 		}
-		log.Tracef("stream %v actively closed", s.id)
+		log.Tracef("stream %v actively closed. seq %v", s.id, f.Seq)
 	} else {
 		log.Tracef("stream %v passively closed", s.id)
 	}
diff --git a/internal/multiplex/stream.go b/internal/multiplex/stream.go
index 7d2c908..0b6974e 100644
--- a/internal/multiplex/stream.go
+++ b/internal/multiplex/stream.go
@@ -20,7 +20,6 @@ type Stream struct {
 
 	recvBuf recvBuffer
 
-	// atomic
 	nextSendSeq uint64
 
 	writingM sync.Mutex
@@ -74,10 +73,10 @@ func (s *Stream) Read(buf []byte) (n int, err error) {
 	}
 
 	n, err = s.recvBuf.Read(buf)
+	log.Tracef("%v read from stream %v with err %v", n, s.id, err)
 	if err == io.EOF {
 		return n, ErrBrokenStream
 	}
-	log.Tracef("%v read from stream %v with err %v", n, s.id, err)
 	return
 }
 
@@ -91,14 +90,7 @@ func (s *Stream) WriteTo(w io.Writer) (int64, error) {
 	return n, nil
 }
 
-func (s *Stream) writePayload(seq uint64, payload []byte) error {
-	f := &Frame{
-		StreamID: s.id,
-		Seq:      seq,
-		Closing:  C_NOOP,
-		Payload:  payload,
-	}
-
+func (s *Stream) sendFrame(f *Frame) error {
 	var cipherTextLen int
 	cipherTextLen, err := s.session.Obfs(f, s.obfsBuf)
 	if err != nil {
@@ -106,7 +98,7 @@ func (s *Stream) writePayload(seq uint64, payload []byte) error {
 	}
 
 	_, err = s.session.sb.send(s.obfsBuf[:cipherTextLen], &s.assignedConnId)
-	log.Tracef("%v sent to remote through stream %v with err %v", len(payload), s.id, err)
+	log.Tracef("%v sent to remote through stream %v with err %v. seq: %v", len(f.Payload), s.id, err, f.Seq)
 	if err != nil {
 		if err == errBrokenSwitchboard {
 			s.session.SetTerminalMsg(err.Error())
@@ -139,7 +131,14 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 			}
 			framePayload = in[n : s.session.maxStreamUnitWrite+n]
 		}
-		err = s.writePayload(atomic.AddUint64(&s.nextSendSeq, 1)-1, framePayload)
+		f := &Frame{
+			StreamID: s.id,
+			Seq:      s.nextSendSeq,
+			Closing:  C_NOOP,
+			Payload:  framePayload,
+		}
+		s.nextSendSeq++
+		err = s.sendFrame(f)
 		if err != nil {
 			return
 		}
@@ -149,8 +148,6 @@ func (s *Stream) Write(in []byte) (n int, err error) {
 }
 
 func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
-	s.writingM.Lock()
-	defer s.writingM.Unlock()
 	if s.obfsBuf == nil {
 		s.obfsBuf = make([]byte, s.session.SendBufferSize)
 	}
@@ -160,10 +157,20 @@ func (s *Stream) ReadFrom(r io.Reader) (n int64, err error) {
 			return n, er
 		}
 		if s.isClosed() {
-			return 0, ErrBrokenStream
+			return n, ErrBrokenStream
 		}
-		seq := atomic.AddUint64(&s.nextSendSeq, 1) - 1
-		err = s.writePayload(seq, s.obfsBuf[HEADER_LEN:HEADER_LEN+read])
+
+		s.writingM.Lock()
+		f := &Frame{
+			StreamID: s.id,
+			Seq:      s.nextSendSeq,
+			Closing:  C_NOOP,
+			Payload:  s.obfsBuf[HEADER_LEN : HEADER_LEN+read],
+		}
+		s.nextSendSeq++
+		err = s.sendFrame(f)
+		s.writingM.Unlock()
+
 		if err != nil {
 			return
 		}
@@ -177,6 +184,9 @@ func (s *Stream) passiveClose() error {
 
 // active close. Close locally and tell the remote that this stream is being closed
 func (s *Stream) Close() error {
+	s.writingM.Lock()
+	defer s.writingM.Unlock()
+
 	return s.session.closeStream(s, true)
 }