diff --git a/src/internet/model/tcp-socket-base.cc b/src/internet/model/tcp-socket-base.cc
index 4958b466c..9c4425e11 100644
--- a/src/internet/model/tcp-socket-base.cc
+++ b/src/internet/model/tcp-socket-base.cc
@@ -3060,6 +3060,7 @@ TcpSocketBase::PersistTimeout ()
   NS_LOG_LOGIC ("PersistTimeout expired at " << Simulator::Now ().GetSeconds ());
   m_persistTimeout = std::min (Seconds (60), Time (2 * m_persistTimeout)); // max persist timeout = 60s
   Ptr<Packet> p = m_txBuffer->CopyFromSequence (1, m_tcb->m_nextTxSequence);
+  m_txBuffer->ResetLastSegmentSent ();
   TcpHeader tcpHeader;
   tcpHeader.SetSequenceNumber (m_tcb->m_nextTxSequence);
   tcpHeader.SetAckNumber (m_rxBuffer->NextRxSequence ());