diff --git a/src/FactSystem/Fact.h b/src/FactSystem/Fact.h
index f8ffcc1589e046c27c43b384c6b5db38b4bb0438..0b1df3d3042291c70a2837a290ca27289464b025 100644
--- a/src/FactSystem/Fact.h
+++ b/src/FactSystem/Fact.h
@@ -30,13 +30,13 @@ class Fact : public QObject
     Q_OBJECT
     
 public:
-    Fact(QObject* parent = NULL);
-    Fact(int componentId, QString name, FactMetaData::ValueType_t type, QObject* parent = NULL);
-    Fact(const Fact& other, QObject* parent = NULL);
+    Fact(QObject* parent = nullptr);
+    Fact(int componentId, QString name, FactMetaData::ValueType_t type, QObject* parent = nullptr);
+    Fact(const Fact& other, QObject* parent = nullptr);
 
     /// Creates a Fact using the name and type from metaData. Also calls QGCCorePlugin::adjustSettingsMetaData allowing
     /// custom builds to override the metadata.
-    Fact(const QString& settingsGroup, FactMetaData* metaData, QObject* parent = NULL);
+    Fact(const QString& settingsGroup, FactMetaData* metaData, QObject* parent = nullptr);
 
     const Fact& operator=(const Fact& other);
 
diff --git a/src/FactSystem/FactGroup.cc b/src/FactSystem/FactGroup.cc
index 55aedaf9869c6f4bc047fc5954ef7414c5918139..18daa57e5597de561b020ea43bb9fcb18fcae623 100644
--- a/src/FactSystem/FactGroup.cc
+++ b/src/FactSystem/FactGroup.cc
@@ -53,19 +53,19 @@ void FactGroup::_setupTimer()
 
 Fact* FactGroup::getFact(const QString& name)
 {
-    Fact* fact = NULL;
+    Fact* fact = nullptr;
 
     if (name.contains(".")) {
         QStringList parts = name.split(".");
         if (parts.count() != 2) {
             qWarning() << "Only single level of hierarchy supported";
-            return NULL;
+            return nullptr;
         }
 
         FactGroup * factGroup = getFactGroup(parts[0]);
         if (!factGroup) {
             qWarning() << "Unknown FactGroup" << parts[0];
-            return NULL;
+            return nullptr;
         }
 
         return factGroup->getFact(parts[1]);
@@ -83,7 +83,7 @@ Fact* FactGroup::getFact(const QString& name)
 
 FactGroup* FactGroup::getFactGroup(const QString& name)
 {
-    FactGroup* factGroup = NULL;
+    FactGroup* factGroup = nullptr;
 
     if (_nameToFactGroupMap.contains(name)) {
         factGroup = _nameToFactGroupMap[name];
diff --git a/src/FactSystem/FactGroup.h b/src/FactSystem/FactGroup.h
index 9e8320fca0cfcc977f8f70f23e23aac04a58ba6b..3c7f09c6587d47f8df7cf0b36ab45de69d191f1b 100644
--- a/src/FactSystem/FactGroup.h
+++ b/src/FactSystem/FactGroup.h
@@ -26,8 +26,8 @@ class FactGroup : public QObject
     Q_OBJECT
     
 public:
-    FactGroup(int updateRateMsecs, const QString& metaDataFile, QObject* parent = NULL);
-    FactGroup(int updateRateMsecs, QObject* parent = NULL);
+    FactGroup(int updateRateMsecs, const QString& metaDataFile, QObject* parent = nullptr);
+    FactGroup(int updateRateMsecs, QObject* parent = nullptr);
 
     Q_PROPERTY(QStringList factNames        READ factNames      CONSTANT)
     Q_PROPERTY(QStringList factGroupNames   READ factGroupNames CONSTANT)
diff --git a/src/FactSystem/FactMetaData.cc b/src/FactSystem/FactMetaData.cc
index 777a650a46822cf4d29d88bdd777ec383aa78fd4..4316a9473387ddebd6d22d5cd5b358fc8994aa9b 100644
--- a/src/FactSystem/FactMetaData.cc
+++ b/src/FactSystem/FactMetaData.cc
@@ -933,7 +933,7 @@ const FactMetaData::AppSettingsTranslation_s* FactMetaData::_findAppSettingsDist
             return pAppSettingsTranslation;
         }
     }
-    return NULL;
+    return nullptr;
 }
 
 const FactMetaData::AppSettingsTranslation_s* FactMetaData::_findAppSettingsAreaUnitsTranslation(const QString& rawUnits)
@@ -953,7 +953,7 @@ const FactMetaData::AppSettingsTranslation_s* FactMetaData::_findAppSettingsArea
         }
     }
 
-    return NULL;
+    return nullptr;
 }
 
 QVariant FactMetaData::metersToAppSettingsDistanceUnits(const QVariant& meters)
diff --git a/src/FactSystem/FactSystemTestBase.cc b/src/FactSystem/FactSystemTestBase.cc
index 8a75ab331f40e2f0c90d0569222da30c26efa0ca..ce6ca4d0a11c5cd11a8dc2cf98ab83563ad72e12 100644
--- a/src/FactSystem/FactSystemTestBase.cc
+++ b/src/FactSystem/FactSystemTestBase.cc
@@ -48,7 +48,7 @@ void FactSystemTestBase::_parameter_default_component_id_test(void)
 {
     QVERIFY(_vehicle->parameterManager()->parameterExists(FactSystem::defaultComponentId, "RC_MAP_THROTTLE"));
     Fact* fact = _vehicle->parameterManager()->getParameter(FactSystem::defaultComponentId, "RC_MAP_THROTTLE");
-    QVERIFY(fact != NULL);
+    QVERIFY(fact != nullptr);
     QVariant factValue = fact->rawValue();
     QCOMPARE(factValue.isValid(), true);
 
@@ -59,7 +59,7 @@ void FactSystemTestBase::_parameter_specific_component_id_test(void)
 {
     QVERIFY(_vehicle->parameterManager()->parameterExists(MAV_COMP_ID_AUTOPILOT1, "RC_MAP_THROTTLE"));
     Fact* fact = _vehicle->parameterManager()->getParameter(MAV_COMP_ID_AUTOPILOT1, "RC_MAP_THROTTLE");
-    QVERIFY(fact != NULL);
+    QVERIFY(fact != nullptr);
     QVariant factValue = fact->rawValue();
     QCOMPARE(factValue.isValid(), true);
     QCOMPARE(factValue.toInt(), 3);
diff --git a/src/FactSystem/FactValueSliderListModel.h b/src/FactSystem/FactValueSliderListModel.h
index 21914b563c676a5d9b3b3d3e511ce282c5794f11..6dd50f4ae53ffd7d0c3a90f41fe8c74a7bf3888c 100644
--- a/src/FactSystem/FactValueSliderListModel.h
+++ b/src/FactSystem/FactValueSliderListModel.h
@@ -19,7 +19,7 @@ class FactValueSliderListModel : public QAbstractListModel
     Q_OBJECT
     
 public:
-    FactValueSliderListModel(Fact& fact, QObject* parent = NULL);
+    FactValueSliderListModel(Fact& fact, QObject* parent = nullptr);
     ~FactValueSliderListModel();
 
     /// The initial value of the Fact at the meta data specified decimal place precision
diff --git a/src/FactSystem/ParameterManager.cc b/src/FactSystem/ParameterManager.cc
index b71dfedbf21b812103666de01aaf927784b85ac9..322d87e001ebda247166fe2fb56908999fca0c24 100644
--- a/src/FactSystem/ParameterManager.cc
+++ b/src/FactSystem/ParameterManager.cc
@@ -35,7 +35,7 @@ const char* ParameterManager::_jsonParamValueKey =          "value";
 ParameterManager::ParameterManager(Vehicle* vehicle)
     : QObject                           (vehicle)
     , _vehicle                          (vehicle)
-    , _mavlink                          (NULL)
+    , _mavlink                          (nullptr)
     , _loadProgress                     (0.0)
     , _parametersReady                  (false)
     , _missingParameters                (false)
@@ -45,7 +45,7 @@ ParameterManager::ParameterManager(Vehicle* vehicle)
     , _metaDataAddedToFacts             (false)
     , _logReplay                        (vehicle->priorityLink() && vehicle->priorityLink()->isLogReplay())
     , _parameterSetMajorVersion         (-1)
-    , _parameterMetaData                (NULL)
+    , _parameterMetaData                (nullptr)
     , _prevWaitingReadParamIndexCount   (0)
     , _prevWaitingReadParamNameCount    (0)
     , _prevWaitingWriteParamNameCount   (0)
@@ -330,7 +330,7 @@ void ParameterManager::_parameterUpdate(int vehicleId, int componentId, QString
 
     _dataMutex.unlock();
 
-    Fact* fact = NULL;
+    Fact* fact = nullptr;
     if (_mapParameterName2Variant[componentId].contains(parameterName)) {
         fact = _mapParameterName2Variant[componentId][parameterName].value<Fact*>();
     }
@@ -1052,7 +1052,7 @@ void ParameterManager::_clearMetaData(void)
 {
     if (_parameterMetaData) {
         _parameterMetaData->deleteLater();
-        _parameterMetaData = NULL;
+        _parameterMetaData = nullptr;
     }
 }
 
@@ -1288,7 +1288,7 @@ void ParameterManager::cacheMetaDataFile(const QString& metaDataFile, MAV_AUTOPI
 
     // Find the cache hit closest to this new file
     int cacheMajorVersion, cacheMinorVersion;
-    QString cacheHit = ParameterManager::parameterMetaDataFile(NULL, firmwareType, newMajorVersion, cacheMajorVersion, cacheMinorVersion);
+    QString cacheHit = ParameterManager::parameterMetaDataFile(nullptr, firmwareType, newMajorVersion, cacheMajorVersion, cacheMinorVersion);
     qCDebug(ParameterManagerLog) << "ParameterManager::cacheMetaDataFile cacheHit file:firmware:major;minor" << cacheHit << cacheMajorVersion << cacheMinorVersion;
 
     bool cacheNewFile = false;