diff --git a/src/internet/model/tcp-socket-base.cc b/src/internet/model/tcp-socket-base.cc
index ef5048959..95a4a0d1a 100644
--- a/src/internet/model/tcp-socket-base.cc
+++ b/src/internet/model/tcp-socket-base.cc
@@ -440,6 +440,7 @@ TcpSocketBase::TcpSocketBase (const TcpSocketBase& sock)
 
   ok = m_tcb->TraceConnectWithoutContext ("HighestSequence",
                                           MakeCallback (&TcpSocketBase::UpdateHighTxMark, this));
+  NS_ASSERT (ok == true);
 }
 
 TcpSocketBase::~TcpSocketBase (void)