diff --git a/libraries/avatars/src/AvatarData.cpp b/libraries/avatars/src/AvatarData.cpp
index 3bd147d398..f64504d662 100644
--- a/libraries/avatars/src/AvatarData.cpp
+++ b/libraries/avatars/src/AvatarData.cpp
@@ -966,7 +966,8 @@ bool AvatarData::hasIdentityChangedAfterParsing(NLPacket& packet) {
 QByteArray AvatarData::identityByteArray() {
     QByteArray identityData;
     QDataStream identityStream(&identityData, QIODevice::Append);
-    const QUrl& urlToSend = (_skeletonModelURL == AvatarData::defaultFullAvatarModelUrl()) ? QUrl("") : _skeletonModelURL;
+    QUrl emptyURL("");
+    const QUrl& urlToSend = (_skeletonModelURL == AvatarData::defaultFullAvatarModelUrl()) ? emptyURL : _skeletonModelURL;
 
     identityStream << QUuid() << _faceModelURL << urlToSend << _attachmentData << _displayName;
 
diff --git a/libraries/networking/src/NLPacketList.cpp b/libraries/networking/src/NLPacketList.cpp
index 3b115c558b..318fb037a1 100644
--- a/libraries/networking/src/NLPacketList.cpp
+++ b/libraries/networking/src/NLPacketList.cpp
@@ -23,7 +23,8 @@ std::unique_ptr<NLPacketList> NLPacketList::create(PacketType packetType, QByteA
 }
 
 std::unique_ptr<NLPacketList> NLPacketList::fromPacketList(std::unique_ptr<PacketList> packetList) {
-    auto nlPacketList = std::unique_ptr<NLPacketList>(new NLPacketList(std::move(*packetList.release())));    nlPacketList->open(ReadOnly);
+    auto nlPacketList = std::unique_ptr<NLPacketList>(new NLPacketList(std::move(*packetList.release())));
+    nlPacketList->open(ReadOnly);
     return nlPacketList;
 }
 
diff --git a/libraries/networking/src/SentPacketHistory.cpp b/libraries/networking/src/SentPacketHistory.cpp
index c6eec8eb63..14b4677fc3 100644
--- a/libraries/networking/src/SentPacketHistory.cpp
+++ b/libraries/networking/src/SentPacketHistory.cpp
@@ -35,6 +35,7 @@ void SentPacketHistory::packetSent(uint16_t sequenceNumber, const NLPacket& pack
     }
     _newestSequenceNumber = sequenceNumber;
 
+    QWriteLocker locker(&_packetsLock);
     _sentPackets.insert(NLPacket::createCopy(packet));
 }
 
@@ -48,6 +49,7 @@ const NLPacket* SentPacketHistory::getPacket(uint16_t sequenceNumber) const {
     if (seqDiff < 0) {
         seqDiff += UINT16_RANGE;
     }
-
+    
+    QReadLocker locker(&_packetsLock);
     return _sentPackets.get(seqDiff)->get();
 }
diff --git a/libraries/networking/src/SentPacketHistory.h b/libraries/networking/src/SentPacketHistory.h
index 1808e0020b..72150658e3 100644
--- a/libraries/networking/src/SentPacketHistory.h
+++ b/libraries/networking/src/SentPacketHistory.h
@@ -12,7 +12,9 @@
 #define hifi_SentPacketHistory_h
 
 #include <stdint.h>
-#include <qbytearray.h>
+
+#include <QtCore/QByteArray>
+#include <QtCore/QReadWriteLock>
 
 #include "NLPacket.h"
 #include "RingBufferHistory.h"
@@ -29,6 +31,7 @@ public:
     const NLPacket* getPacket(uint16_t sequenceNumber) const;
 
 private:
+    mutable QReadWriteLock _packetsLock { QReadWriteLock::Recursive };
     RingBufferHistory<std::unique_ptr<NLPacket>> _sentPackets;    // circular buffer
 
     uint16_t _newestSequenceNumber;
diff --git a/libraries/networking/src/udt/CongestionControl.cpp b/libraries/networking/src/udt/CongestionControl.cpp
index ea46d60acb..c1feae3911 100644
--- a/libraries/networking/src/udt/CongestionControl.cpp
+++ b/libraries/networking/src/udt/CongestionControl.cpp
@@ -161,13 +161,16 @@ void DefaultCC::onLoss(SequenceNumber rangeStart, SequenceNumber rangeEnd) {
         
         _lastDecreaseMaxSeq = _sendCurrSeqNum;
         
-        // avoid synchronous rate decrease across connections using randomization
-        std::random_device rd;
-        std::mt19937 generator(rd());
-        std::uniform_int_distribution<> distribution(1, _avgNAKNum);
-        
-        _randomDecreaseThreshold = distribution(generator);
-        
+        if (_avgNAKNum < 1) {
+            _randomDecreaseThreshold = 1;
+        } else {
+            // avoid synchronous rate decrease across connections using randomization
+            std::random_device rd;
+            std::mt19937 generator(rd());
+            std::uniform_int_distribution<> distribution(1, std::max(1, _avgNAKNum));
+
+            _randomDecreaseThreshold = distribution(generator);
+        }
     } else if ((_decreaseCount++ < MAX_DECREASES_PER_CONGESTION_EPOCH) && ((++_nakCount % _randomDecreaseThreshold) == 0)) {
         // there have been fewer than MAX_DECREASES_PER_CONGESTION_EPOCH AND this NAK matches the random count at which we
         // decided we would decrease the packet send period
diff --git a/libraries/octree/src/OctreeEditPacketSender.cpp b/libraries/octree/src/OctreeEditPacketSender.cpp
index 1be271cbdd..495effc825 100644
--- a/libraries/octree/src/OctreeEditPacketSender.cpp
+++ b/libraries/octree/src/OctreeEditPacketSender.cpp
@@ -346,6 +346,7 @@ void OctreeEditPacketSender::processNackPacket(NLPacket& packet, SharedNodePoint
     if (_sentPacketHistories.count(sendingNode->getUUID()) == 0) {
         return;
     }
+    
     const SentPacketHistory& sentPacketHistory = _sentPacketHistories[sendingNode->getUUID()];
 
     // read sequence numbers and queue packets for resend