diff --git a/daemon/face/lp-reliability.cpp b/daemon/face/lp-reliability.cpp
index ca5a216..4ff2ac5 100644
--- a/daemon/face/lp-reliability.cpp
+++ b/daemon/face/lp-reliability.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2017,  Regents of the University of California,
+ * Copyright (c) 2014-2018,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -82,7 +82,7 @@
                                                  std::forward_as_tuple(frag));
     unackedFragsIt->second.sendTime = sendTime;
     unackedFragsIt->second.rtoTimer =
-      scheduler::schedule(m_rto.computeRto(), bind(&LpReliability::onLpPacketLost, this, unackedFragsIt));
+      scheduler::schedule(m_rto.computeRto(), bind(&LpReliability::onLpPacketLost, this, txSeq));
     unackedFragsIt->second.netPkt = netPkt;
 
     if (m_unackedFrags.size() == 1) {
@@ -127,9 +127,20 @@
     // packet. Potentially increment the start of the window.
     onLpPacketAcknowledged(fragIt);
 
+    // This set contains TxSequences that have been removed by onLpPacketLost below because they
+    // were part of a network packet that was removed due to a fragment exceeding retx, as well as
+    // any other TxSequences removed by onLpPacketLost. This prevents onLpPacketLost from being
+    // called later for an invalid iterator.
+    std::set<lp::Sequence> removedLpPackets;
+
     // Resend or fail fragments considered lost. Potentially increment the start of the window.
-    for (UnackedFrags::iterator txSeqIt : lostLpPackets) {
-      this->onLpPacketLost(txSeqIt);
+    for (lp::Sequence txSeq : lostLpPackets) {
+      if (removedLpPackets.find(txSeq) == removedLpPackets.end()) {
+        auto removedThisTxSeq = this->onLpPacketLost(txSeq);
+        for (auto removedTxSeq : removedThisTxSeq) {
+          removedLpPackets.insert(removedTxSeq);
+        }
+      }
     }
   }
 
@@ -206,10 +217,10 @@
   m_isIdleAckTimerRunning = false;
 }
 
-std::vector<LpReliability::UnackedFrags::iterator>
+std::vector<lp::Sequence>
 LpReliability::findLostLpPackets(LpReliability::UnackedFrags::iterator ackIt)
 {
-  std::vector<UnackedFrags::iterator> lostLpPackets;
+  std::vector<lp::Sequence> lostLpPackets;
 
   for (auto it = m_firstUnackedFrag; ; ++it) {
     if (it == m_unackedFrags.end()) {
@@ -224,27 +235,30 @@
     unackedFrag.nGreaterSeqAcks++;
 
     if (unackedFrag.nGreaterSeqAcks >= m_options.seqNumLossThreshold) {
-      lostLpPackets.push_back(it);
+      lostLpPackets.push_back(it->first);
     }
   }
 
   return lostLpPackets;
 }
 
-void
-LpReliability::onLpPacketLost(UnackedFrags::iterator txSeqIt)
+std::vector<lp::Sequence>
+LpReliability::onLpPacketLost(lp::Sequence txSeq)
 {
-  BOOST_ASSERT(m_unackedFrags.count(txSeqIt->first) > 0);
+  BOOST_ASSERT(m_unackedFrags.count(txSeq) > 0);
+  auto txSeqIt = m_unackedFrags.find(txSeq);
 
   auto& txFrag = txSeqIt->second;
   txFrag.rtoTimer.cancel();
   auto netPkt = txFrag.netPkt;
+  std::vector<lp::Sequence> removedThisTxSeq;
 
   // Check if maximum number of retransmissions exceeded
   if (txFrag.retxCount >= m_options.maxRetx) {
     // Delete all LpPackets of NetPkt from m_unackedFrags (except this one)
     for (size_t i = 0; i < netPkt->unackedFrags.size(); i++) {
       if (netPkt->unackedFrags[i] != txSeqIt) {
+        removedThisTxSeq.push_back(netPkt->unackedFrags[i]->first);
         deleteUnackedFrag(netPkt->unackedFrags[i]);
       }
     }
@@ -260,6 +274,7 @@
       onDroppedInterest(Interest(frag));
     }
 
+    removedThisTxSeq.push_back(txSeqIt->first);
     deleteUnackedFrag(txSeqIt);
   }
   else {
@@ -284,6 +299,7 @@
     BOOST_ASSERT(fragInNetPkt != netPkt->unackedFrags.end());
     *fragInNetPkt = newTxFragIt;
 
+    removedThisTxSeq.push_back(txSeqIt->first);
     deleteUnackedFrag(txSeqIt);
 
     // Retransmit fragment
@@ -291,8 +307,10 @@
 
     // Start RTO timer for this sequence
     newTxFrag.rtoTimer = scheduler::schedule(m_rto.computeRto(),
-                                          bind(&LpReliability::onLpPacketLost, this, newTxFragIt));
+                                          bind(&LpReliability::onLpPacketLost, this, newTxSeq));
   }
+
+  return removedThisTxSeq;
 }
 
 void
diff --git a/daemon/face/lp-reliability.hpp b/daemon/face/lp-reliability.hpp
index 328edb0..896cc0e 100644
--- a/daemon/face/lp-reliability.hpp
+++ b/daemon/face/lp-reliability.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2017,  Regents of the University of California,
+ * Copyright (c) 2014-2018,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -135,15 +135,16 @@
   /** \brief find and mark as lost fragments where a configurable number of Acks
    *         (\p m_options.seqNumLossThreshold) have been received for greater TxSequence numbers
    *  \param ackIt iterator pointing to acknowledged fragment
-   *  \return vector containing iterators to fragments marked lost by this mechanism
+   *  \return vector containing TxSequences of fragments marked lost by this mechanism
    */
-  std::vector<UnackedFrags::iterator>
+  std::vector<lp::Sequence>
   findLostLpPackets(UnackedFrags::iterator ackIt);
 
   /** \brief resend (or give up on) a lost fragment
+   *  \return vector of the TxSequences of fragments removed due to a network packet being removed
    */
-  void
-  onLpPacketLost(UnackedFrags::iterator txSeqIt);
+  std::vector<lp::Sequence>
+  onLpPacketLost(lp::Sequence txSeq);
 
   /** \brief remove the fragment with the given sequence number from the map of unacknowledged
    *         fragments, as well as its associated network packet (if any)
diff --git a/tests/daemon/face/lp-reliability.t.cpp b/tests/daemon/face/lp-reliability.t.cpp
index 4baeb6b..907cdc3 100644
--- a/tests/daemon/face/lp-reliability.t.cpp
+++ b/tests/daemon/face/lp-reliability.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2017,  Regents of the University of California,
+ * Copyright (c) 2014-2018,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -67,25 +67,25 @@
 
 private:
   void
-  doSendInterest(const Interest& interest) override
+  doSendInterest(const Interest&) final
   {
     BOOST_ASSERT(false);
   }
 
   void
-  doSendData(const Data& data) override
+  doSendData(const Data&) final
   {
     BOOST_ASSERT(false);
   }
 
   void
-  doSendNack(const lp::Nack& nack) override
+  doSendNack(const lp::Nack&) final
   {
     BOOST_ASSERT(false);
   }
 
   void
-  doReceivePacket(Transport::Packet&& packet) override
+  doReceivePacket(Transport::Packet&&) final
   {
     BOOST_ASSERT(false);
   }
@@ -119,12 +119,6 @@
                        });
   }
 
-  LpReliability::UnackedFrags::iterator
-  getIteratorFromTxSeq(lp::Sequence txSeq)
-  {
-    return reliability->m_unackedFrags.find(txSeq);
-  }
-
   /** \brief make an LpPacket with fragment of specified size
    *  \param pktNo packet identifier, which can be extracted with \p getPktNo
    *  \param payloadSize total payload size; if this is less than 4, 4 will be used
@@ -161,7 +155,7 @@
     return value;
   }
 
-public:
+protected:
   unique_ptr<DummyLpReliabilityLinkService> linkService;
   unique_ptr<DummyTransport> transport;
   unique_ptr<DummyFace> face;
@@ -170,8 +164,6 @@
 
 BOOST_FIXTURE_TEST_SUITE(TestLpReliability, LpReliabilityFixture)
 
-BOOST_AUTO_TEST_SUITE(Sender)
-
 BOOST_AUTO_TEST_CASE(SendNoFragmentField)
 {
   lp::Packet pkt;
@@ -191,11 +183,12 @@
   lp::Packet pkt2 = makeFrag(3000, 30);
 
   linkService->sendLpPackets({pkt1});
+  BOOST_REQUIRE_EQUAL(transport->sentPackets.size(), 1);
   lp::Packet cached1(transport->sentPackets.front().packet);
   BOOST_REQUIRE(cached1.has<lp::TxSequenceField>());
-  BOOST_CHECK_EQUAL(cached1.get<lp::TxSequenceField>(), 2);
   BOOST_CHECK(!cached1.has<lp::SequenceField>());
   lp::Sequence firstTxSeq = cached1.get<lp::TxSequenceField>();
+  BOOST_CHECK_EQUAL(firstTxSeq, 2);
   BOOST_CHECK_EQUAL(getPktNo(cached1), 1024);
   BOOST_CHECK_EQUAL(linkService->getCounters().nAcknowledged, 0);
   BOOST_CHECK_EQUAL(linkService->getCounters().nRetransmitted, 0);
@@ -214,7 +207,7 @@
   BOOST_CHECK(reliability->m_unackedFrags.at(firstTxSeq).netPkt);
   BOOST_CHECK(reliability->m_unackedFrags.at(firstTxSeq + 1).netPkt);
   BOOST_CHECK_NE(reliability->m_unackedFrags.at(firstTxSeq).netPkt,
-                    reliability->m_unackedFrags.at(firstTxSeq + 1).netPkt);
+                 reliability->m_unackedFrags.at(firstTxSeq + 1).netPkt);
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.at(firstTxSeq).retxCount, 0);
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.at(firstTxSeq + 1).retxCount, 0);
   BOOST_CHECK_EQUAL(reliability->m_firstUnackedFrag->first, firstTxSeq);
@@ -374,7 +367,7 @@
   // 2049 rto: 1000ms, txSeq: 5, started T+250ms, retx 1
   // 2050 rto: 1000ms, txSeq: 4, started T+0ms, retx 0
   advanceClocks(time::milliseconds(1), 250);
-  reliability->onLpPacketLost(getIteratorFromTxSeq(3));
+  reliability->onLpPacketLost(3);
 
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.count(2), 1);
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.count(3), 0);
@@ -408,7 +401,7 @@
   // 2049 rto: 1000ms, txSeq: 6, started T+500ms, retx 2
   // 2050 rto: 1000ms, txSeq: 4, started T+0ms, retx 0
   advanceClocks(time::milliseconds(1), 250);
-  reliability->onLpPacketLost(getIteratorFromTxSeq(5));
+  reliability->onLpPacketLost(5);
 
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.count(2), 1);
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.count(5), 0);
@@ -442,7 +435,7 @@
   // 2049 rto: 1000ms, txSeq: 7, started T+750ms, retx 3
   // 2050 rto: 1000ms, txSeq: 4, started T+0ms, retx 0
   advanceClocks(time::milliseconds(1), 250);
-  reliability->onLpPacketLost(getIteratorFromTxSeq(6));
+  reliability->onLpPacketLost(6);
 
   BOOST_REQUIRE_EQUAL(reliability->m_unackedFrags.count(2), 1);
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.count(6), 0);
@@ -476,7 +469,7 @@
   // 2049 rto: expired, removed
   // 2050 rto: expired, removed
   advanceClocks(time::milliseconds(1), 100);
-  reliability->onLpPacketLost(getIteratorFromTxSeq(7));
+  reliability->onLpPacketLost(7);
 
   BOOST_CHECK_EQUAL(reliability->m_unackedFrags.size(), 0);
   BOOST_CHECK_EQUAL(reliability->m_ackQueue.size(), 0);
@@ -515,11 +508,14 @@
   BOOST_CHECK_EQUAL(linkService->getCounters().nDroppedInterests, 0);
 }
 
-BOOST_AUTO_TEST_CASE(LossByGreaterAcks) // detect loss by 3x greater Acks, also tests wraparound
+BOOST_AUTO_TEST_CASE(LossByGreaterAcks)
 {
+  // Detect loss by 3x greater Acks, also tests wraparound
+
   reliability->m_lastTxSeqNo = 0xFFFFFFFFFFFFFFFE;
 
-  // Passed to sendLpPackets individually since they are from separate, non-fragmented network packets
+  // Passed to sendLpPackets individually since they are
+  // from separate, non-fragmented network packets
   linkService->sendLpPackets({makeFrag(1, 50)});
   linkService->sendLpPackets({makeFrag(2, 50)});
   linkService->sendLpPackets({makeFrag(3, 50)});
@@ -653,6 +649,44 @@
   BOOST_CHECK_EQUAL(linkService->getCounters().nDroppedInterests, 0);
 }
 
+BOOST_AUTO_TEST_CASE(SkipFragmentsRemovedInRtt)
+{
+  auto opts = linkService->getOptions();
+  opts.reliabilityOptions.maxRetx = 0; // just to make the test case shorter
+  opts.reliabilityOptions.seqNumLossThreshold = 3;
+  linkService->setOptions(opts);
+
+  lp::Packet frag1 = makeFrag(5001);
+  lp::Packet frag2 = makeFrag(5002);
+  linkService->sendLpPackets({frag1, frag2}); // First packet has 2 fragments
+  linkService->sendLpPackets({makeFrag(5003)});
+  linkService->sendLpPackets({makeFrag(5004)});
+  linkService->sendLpPackets({makeFrag(5005)});
+
+  BOOST_CHECK_EQUAL(transport->sentPackets.size(), 5);
+  BOOST_CHECK_EQUAL(reliability->m_unackedFrags.size(), 5);
+
+  lp::Sequence firstTxSeq = reliability->m_firstUnackedFrag->first;
+
+  // Ack the last 2 packets
+  lp::Packet ackPkt1;
+  ackPkt1.add<lp::AckField>(firstTxSeq + 4);
+  ackPkt1.add<lp::AckField>(firstTxSeq + 3);
+  reliability->processIncomingPacket(ackPkt1);
+
+  BOOST_CHECK_EQUAL(reliability->m_unackedFrags.size(), 3);
+  BOOST_CHECK_EQUAL(reliability->m_unackedFrags.at(firstTxSeq).nGreaterSeqAcks, 2);
+  BOOST_CHECK_EQUAL(reliability->m_unackedFrags.at(firstTxSeq + 1).nGreaterSeqAcks, 2);
+
+  // Ack the third packet (5003)
+  // This triggers a "loss by greater Acks" for packets 5001 and 5002
+  lp::Packet ackPkt2;
+  ackPkt2.add<lp::AckField>(firstTxSeq + 2);
+  reliability->processIncomingPacket(ackPkt2); // tests crash/assert reported in bug #4479
+
+  BOOST_CHECK_EQUAL(reliability->m_unackedFrags.size(), 0);
+}
+
 BOOST_AUTO_TEST_CASE(CancelLossNotificationOnAck)
 {
   reliability->onDroppedInterest.connect([] (const Interest&) {
@@ -677,10 +711,6 @@
   BOOST_CHECK_EQUAL(linkService->getCounters().nDroppedInterests, 0);
 }
 
-BOOST_AUTO_TEST_SUITE_END() // Sender
-
-BOOST_AUTO_TEST_SUITE(Receiver)
-
 BOOST_AUTO_TEST_CASE(ProcessIncomingPacket)
 {
   BOOST_CHECK(!reliability->m_isIdleAckTimerRunning);
@@ -743,7 +773,7 @@
 
   BOOST_CHECK(!reliability->m_ackQueue.empty());
 
-  for (int i = 0; i < 5; i++) {
+  for (uint32_t i = 0; i < 5; i++) {
     lp::Packet pkt = makeFrag(i, 60);
     linkService->sendLpPackets({pkt});
 
@@ -923,7 +953,7 @@
 
   // given Ack of size 6 and MTU of 1500, 249 Acks/IDLE packet
   BOOST_REQUIRE_EQUAL(transport->sentPackets.size(), 5);
-  for (int i = 0; i < 4; i++) {
+  for (size_t i = 0; i < 4; i++) {
     lp::Packet sentPkt(transport->sentPackets[i].packet);
     BOOST_CHECK(!sentPkt.has<lp::TxSequenceField>());
     BOOST_CHECK_EQUAL(sentPkt.count<lp::AckField>(), 249);
@@ -956,7 +986,7 @@
 
   // given Ack of size 6 and MTU of 1500, 249 Acks/IDLE packet
   BOOST_REQUIRE_EQUAL(transport->sentPackets.size(), 10);
-  for (int i = 5; i < 9; i++) {
+  for (size_t i = 5; i < 9; i++) {
     lp::Packet sentPkt(transport->sentPackets[i].packet);
     BOOST_CHECK(!sentPkt.has<lp::TxSequenceField>());
     BOOST_CHECK_EQUAL(sentPkt.count<lp::AckField>(), 249);
@@ -982,7 +1012,7 @@
   // given Ack of size 8 and MTU of 1500, approx 187 Acks/IDLE packet
   BOOST_CHECK(!reliability->m_isIdleAckTimerRunning);
   BOOST_REQUIRE_EQUAL(transport->sentPackets.size(), 16);
-  for (int i = 10; i < 15; i++) {
+  for (size_t i = 10; i < 15; i++) {
     lp::Packet sentPkt(transport->sentPackets[i].packet);
     BOOST_CHECK(!sentPkt.has<lp::TxSequenceField>());
     BOOST_CHECK_EQUAL(sentPkt.count<lp::AckField>(), 187);
@@ -1002,8 +1032,6 @@
   BOOST_CHECK_EQUAL(reliability->m_ackQueue.size(), 0);
 }
 
-BOOST_AUTO_TEST_SUITE_END() // Receiver
-
 BOOST_AUTO_TEST_SUITE_END() // TestLpReliability
 BOOST_AUTO_TEST_SUITE_END() // Face