diff --git a/ssh/mux.go b/ssh/mux.go
index a2af7f4..fb54c8b 100644
--- a/ssh/mux.go
+++ b/ssh/mux.go
@@ -131,6 +131,9 @@
 
 func (m *mux) sendMessage(msg interface{}) error {
 	p := Marshal(msg)
+	if debugMux {
+		log.Printf("send global(%d): %#v", m.chanList.offset, msg)
+	}
 	return m.conn.writePacket(p)
 }