diff --git a/src/comm/BluetoothLink.h b/src/comm/BluetoothLink.h
index 484c372045094cf0ed35a2cf5ab423a47c51119a..302120a491d45b70e9215216d56849c427a72560 100644
--- a/src/comm/BluetoothLink.h
+++ b/src/comm/BluetoothLink.h
@@ -91,7 +91,7 @@ public:
     QString     devName                 () { return _device.name; }
     QString     address                 ();
     QStringList nameList                () { return _nameList; }
-    bool        scanning                () { return _deviceDiscover != NULL; }
+    bool        scanning                () { return _deviceDiscover != nullptr; }
 
     BluetoothData    device             () { return _device; }
 
diff --git a/src/comm/LinkConfiguration.cc b/src/comm/LinkConfiguration.cc
index 6168ccf6ea3c4dc7085aca7abab8bb7b21dc432f..50a720c802b520a6d771d45957ac14225be59e31 100644
--- a/src/comm/LinkConfiguration.cc
+++ b/src/comm/LinkConfiguration.cc
@@ -55,7 +55,7 @@ LinkConfiguration::LinkConfiguration(LinkConfiguration* copy)
 
 void LinkConfiguration::copyFrom(LinkConfiguration* source)
 {
-    Q_ASSERT(source != NULL);
+    Q_ASSERT(source != nullptr);
     _link       = source->link();
     _name       = source->name();
     _dynamic    = source->isDynamic();
diff --git a/src/comm/LinkInterface.h b/src/comm/LinkInterface.h
index 36c01fb72f6edefb2c9d6a2074428959bc28cb61..e04ecc4ffd776fd03e6524f5fbfa1c84df1720af 100644
--- a/src/comm/LinkInterface.h
+++ b/src/comm/LinkInterface.h
@@ -39,7 +39,7 @@ class LinkInterface : public QThread
 public:    
     virtual ~LinkInterface() {
         stopMavlinkMessagesTimer();
-        _config->setLink(NULL);
+        _config->setLink(nullptr);
     }
 
     Q_PROPERTY(bool active      READ active     NOTIFY activeChanged)
diff --git a/src/comm/MockLink.cc b/src/comm/MockLink.cc
index c5dfffd891fc618ffceff15f7cf31eb4c33d6d84..edce306482ea0e9569022f33fb2bd17f2606f2ff 100644
--- a/src/comm/MockLink.cc
+++ b/src/comm/MockLink.cc
@@ -70,7 +70,7 @@ MockLink::MockLink(SharedLinkConfigurationPointer& config)
     , _vehicleLatitude                      (_defaultVehicleLatitude + ((_vehicleSystemId - 128) * 0.0001))     // Slight offset for each vehicle
     , _vehicleLongitude                     (_defaultVehicleLongitude + ((_vehicleSystemId - 128) * 0.0001))
     , _vehicleAltitude                      (_defaultVehicleAltitude)
-    , _fileServer                           (NULL)
+    , _fileServer                           (nullptr)
     , _sendStatusText                       (false)
     , _apmSendHomePositionOnEmptyList       (false)
     , _failureMode                          (MockConfiguration::FailNone)
diff --git a/src/comm/MockLinkMissionItemHandler.cc b/src/comm/MockLinkMissionItemHandler.cc
index 179826898889e039d3e2bdb8da0354138d43b3a6..cc97b9be82645a61f324c9180ab211b476f9c73f 100644
--- a/src/comm/MockLinkMissionItemHandler.cc
+++ b/src/comm/MockLinkMissionItemHandler.cc
@@ -17,7 +17,7 @@ QGC_LOGGING_CATEGORY(MockLinkMissionItemHandlerLog, "MockLinkMissionItemHandlerL
 
 MockLinkMissionItemHandler::MockLinkMissionItemHandler(MockLink* mockLink, MAVLinkProtocol* mavlinkProtocol)
     : _mockLink(mockLink)
-    , _missionItemResponseTimer(NULL)
+    , _missionItemResponseTimer(nullptr)
     , _failureMode(FailNone)
     , _sendHomePositionOnEmptyList(false)
     , _mavlinkProtocol(mavlinkProtocol)
diff --git a/src/comm/QGCJSBSimLink.cc b/src/comm/QGCJSBSimLink.cc
index 9aee351380f8f0f967567ff289f221e37a233c13..0f4dbc5a4e2f3d32dd1185a5b8e188d41e60cf01 100644
--- a/src/comm/QGCJSBSimLink.cc
+++ b/src/comm/QGCJSBSimLink.cc
@@ -30,8 +30,8 @@
 
 QGCJSBSimLink::QGCJSBSimLink(Vehicle* vehicle, QString startupArguments, QString remoteHost, QHostAddress host, quint16 port)
     : _vehicle(vehicle)
-    , socket(NULL)
-    , process(NULL)
+    , socket(nullptr)
+    , process(nullptr)
     , startupArguments(startupArguments)
 {
     // We're doing it wrong - because the Qt folks got the API wrong:
@@ -337,13 +337,13 @@ bool QGCJSBSimLink::disconnectSimulation()
     {
         process->close();
         delete process;
-        process = NULL;
+        process = nullptr;
     }
     if (socket)
     {
         socket->close();
         delete socket;
-        socket = NULL;
+        socket = nullptr;
     }
 
     connectState = false;
diff --git a/src/comm/QGCXPlaneLink.cc b/src/comm/QGCXPlaneLink.cc
index ed887923685d434001fb18edec126202bb939c54..fe3037e30d1edfa9f98fcb5f0c92feaa9ea8143f 100644
--- a/src/comm/QGCXPlaneLink.cc
+++ b/src/comm/QGCXPlaneLink.cc
@@ -35,9 +35,9 @@ QGCXPlaneLink::QGCXPlaneLink(Vehicle* vehicle, QString remoteHost, QHostAddress
     _vehicle(vehicle),
     remoteHost(QHostAddress("127.0.0.1")),
     remotePort(49000),
-    socket(NULL),
-    process(NULL),
-    terraSync(NULL),
+    socket(nullptr),
+    process(nullptr),
+    terraSync(nullptr),
     barometerOffsetkPa(-8.0f),
     airframeID(QGCXPlaneLink::AIRFRAME_UNKNOWN),
     xPlaneConnected(false),
@@ -75,7 +75,7 @@ QGCXPlaneLink::~QGCXPlaneLink()
     if (socket) {
         socket->close();
         socket->deleteLater();
-        socket = NULL;
+        socket = nullptr;
     }
 }
 
@@ -180,7 +180,7 @@ void QGCXPlaneLink::run()
         emit statusMessage("Binding socket failed!");
 
         socket->deleteLater();
-        socket = NULL;
+        socket = nullptr;
         return;
     }
 
@@ -260,7 +260,7 @@ void QGCXPlaneLink::run()
 
     socket->close();
     socket->deleteLater();
-    socket = NULL;
+    socket = nullptr;
 
     emit simulationDisconnected();
     emit simulationConnected(false);
diff --git a/src/comm/SerialLink.cc b/src/comm/SerialLink.cc
index f9b56249e2b6e6abb6ae36781951441f97bd4020..4190f956d7f08e9d7a89170ecdf9584207260643 100644
--- a/src/comm/SerialLink.cc
+++ b/src/comm/SerialLink.cc
@@ -32,7 +32,7 @@ static QStringList kSupportedBaudRates;
 
 SerialLink::SerialLink(SharedLinkConfigurationPointer& config, bool isPX4Flow)
     : LinkInterface(config, isPX4Flow)
-    , _port(NULL)
+    , _port(nullptr)
     , _bytesRead(0)
     , _stopp(false)
     , _reqReset(false)
@@ -103,7 +103,7 @@ void SerialLink::_disconnect(void)
     if (_port) {
         _port->close();
         _port->deleteLater();
-        _port = NULL;
+        _port = nullptr;
     }
 
 #ifdef __android__
@@ -161,7 +161,7 @@ bool SerialLink::_hardwareConnect(QSerialPort::SerialPortError& error, QString&
             qgcApp()->processEvents(QEventLoop::ExcludeUserInputEvents);
         }
         delete _port;
-        _port = NULL;
+        _port = nullptr;
     }
 
     qCDebug(SerialLinkLog) << "SerialLink: hardwareConnect to " << _serialConfig->portName();
@@ -234,7 +234,7 @@ bool SerialLink::_hardwareConnect(QSerialPort::SerialPortError& error, QString&
         emit communicationUpdate(getName(), tr("Error opening port: %1").arg(_port->errorString()));
         _port->close();
         delete _port;
-        _port = NULL;
+        _port = nullptr;
         return false; // couldn't open serial port
     }
 
diff --git a/src/comm/TCPLink.cc b/src/comm/TCPLink.cc
index ecb27e2b7c9ca43dd1411bff4ab72626045095f1..516b3ff4146aa1c80db015cef69d28749e68e5b8 100644
--- a/src/comm/TCPLink.cc
+++ b/src/comm/TCPLink.cc
@@ -27,7 +27,7 @@
 TCPLink::TCPLink(SharedLinkConfigurationPointer& config)
     : LinkInterface(config)
     , _tcpConfig(qobject_cast<TCPConfiguration*>(config.data()))
-    , _socket(NULL)
+    , _socket(nullptr)
     , _socketIsConnected(false)
 {
     Q_ASSERT(_tcpConfig);
@@ -123,7 +123,7 @@ void TCPLink::_disconnect(void)
         _socket->disconnectFromHost(); // Disconnect tcp
         _socket->waitForDisconnected();        
         _socket->deleteLater(); // Make sure delete happens on correct thread
-        _socket = NULL;
+        _socket = nullptr;
         emit disconnected();
     }
 }
@@ -146,7 +146,7 @@ bool TCPLink::_connect(void)
 
 bool TCPLink::_hardwareConnect()
 {
-    Q_ASSERT(_socket == NULL);
+    Q_ASSERT(_socket == nullptr);
     _socket = new QTcpSocket();
 
     QSignalSpy errorSpy(_socket, static_cast<void (QTcpSocket::*)(QAbstractSocket::SocketError)>(&QTcpSocket::error));
@@ -165,7 +165,7 @@ bool TCPLink::_hardwareConnect()
             emit communicationError(tr("Link Error"), tr("Error on link %1. Connection failed").arg(getName()));
         }
         delete _socket;
-        _socket = NULL;
+        _socket = nullptr;
         return false;
     }
     _socketIsConnected = true;
@@ -281,7 +281,7 @@ void TCPConfiguration::copyFrom(LinkConfiguration *source)
 {
     LinkConfiguration::copyFrom(source);
     TCPConfiguration* usource = dynamic_cast<TCPConfiguration*>(source);
-    Q_ASSERT(usource != NULL);
+    Q_ASSERT(usource != nullptr);
     _port    = usource->port();
     _address = usource->address();
 }
diff --git a/src/comm/UDPLink.cc b/src/comm/UDPLink.cc
index e24b45885af1a10802dbb37c85247f24b116712a..86a1e4d6699e278afc39e6b0de661b15874fba9c 100644
--- a/src/comm/UDPLink.cc
+++ b/src/comm/UDPLink.cc
@@ -80,10 +80,10 @@ static bool contains_target(const QList<UDPCLient*> list, const QHostAddress& ad
 UDPLink::UDPLink(SharedLinkConfigurationPointer& config)
     : LinkInterface(config)
     #if defined(QGC_ZEROCONF_ENABLED)
-    , _dnssServiceRef(NULL)
+    , _dnssServiceRef(nullptr)
     #endif
     , _running(false)
-    , _socket(NULL)
+    , _socket(nullptr)
     , _udpConfig(qobject_cast<UDPConfiguration*>(config.data()))
     , _connectState(false)
 {
@@ -253,7 +253,7 @@ void UDPLink::_disconnect(void)
     if (_socket) {
         // Make sure delete happen on correct thread
         _socket->deleteLater();
-        _socket = NULL;
+        _socket = nullptr;
         emit disconnected();
     }
     _connectState = false;
@@ -281,7 +281,7 @@ bool UDPLink::_hardwareConnect()
 {
     if (_socket) {
         delete _socket;
-        _socket = NULL;
+        _socket = nullptr;
     }
     QHostAddress host = QHostAddress::AnyIPv4;
     _socket = new QUdpSocket(this);