diff --git a/protocol/czar/mux.go b/protocol/czar/mux.go
index 92a9d65..1d6cba9 100644
--- a/protocol/czar/mux.go
+++ b/protocol/czar/mux.go
@@ -11,7 +11,6 @@ import (
 
 // A Stream managed by the multiplexer.
 type Stream struct {
-	idp *Sip
 	idx uint8
 	mux *Mux
 	rbf []byte
@@ -46,7 +45,7 @@ func (s *Stream) Esolc() error {
 		})
 	})
 	s.zo1.Do(func() {
-		s.idp.Put(s.idx)
+		s.mux.idp.Put(s.idx)
 	})
 	return nil
 }
@@ -120,7 +119,6 @@ func (s *Stream) Write(p []byte) (int, error) {
 // NewStream returns a new Stream.
 func NewStream(idx uint8, mux *Mux) *Stream {
 	return &Stream{
-		idp: nil,
 		idx: idx,
 		mux: mux,
 		rbf: make([]byte, 0),
@@ -181,7 +179,6 @@ func (m *Mux) Open() (*Stream, error) {
 		return nil, err
 	}
 	stm = NewStream(idx, m)
-	stm.idp = m.idp
 	m.usb[idx] = stm
 	return stm, nil
 }
@@ -215,9 +212,7 @@ func (m *Mux) Recv() {
 				break
 			}
 			stm = NewStream(idx, m)
-			// The mux server does not need to using an id pool.
-			stm.idp = m.idp
-			stm.idp.Set(idx)
+			m.idp.Set(idx)
 			m.usb[idx] = stm
 			m.ach <- stm
 		case cmd == 0x01:
diff --git a/protocol/czar/sip.go b/protocol/czar/sip.go
index a4482ae..84cb7b4 100644
--- a/protocol/czar/sip.go
+++ b/protocol/czar/sip.go
@@ -43,7 +43,7 @@ func (s *Sip) Set(x uint8) {
 	s.i = s.i.SetBit(s.i, int(x), 1)
 }
 
-// NewSip returns a new sid.
+// NewSip returns a new sip.
 func NewSip() *Sip {
 	return &Sip{
 		i: big.NewInt(0),