diff --git a/src/app/qgsclipboard.cpp b/src/app/qgsclipboard.cpp
index 89734ce39ee..e2373dc6de5 100644
--- a/src/app/qgsclipboard.cpp
+++ b/src/app/qgsclipboard.cpp
@@ -123,7 +123,7 @@ QString QgsClipboard::generateClipboardText() const
             textFields += it->geometry().exportToWkt();
           else
           {
-            textFields += settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+            textFields += QgsApplication::nullRepresentation();
           }
         }
 
diff --git a/src/app/qgsoptions.cpp b/src/app/qgsoptions.cpp
index 982cd54ae61..b2013838e28 100644
--- a/src/app/qgsoptions.cpp
+++ b/src/app/qgsoptions.cpp
@@ -640,7 +640,7 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl )
   else
     mComboCopyFeatureFormat->setCurrentIndex( mComboCopyFeatureFormat->findData( mSettings->value( QStringLiteral( "/qgis/copyGeometryAsWKT" ), true ).toBool() ?
         QgsClipboard::AttributesWithWKT : QgsClipboard::AttributesOnly ) );
-  leNullValue->setText( mSettings->value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+  leNullValue->setText( QgsApplication::nullRepresentation() );
   cbxIgnoreShapeEncoding->setChecked( mSettings->value( QStringLiteral( "/qgis/ignoreShapeEncoding" ), true ).toBool() );
 
   cmbLegendDoubleClickAction->setCurrentIndex( mSettings->value( QStringLiteral( "/qgis/legendDoubleClickAction" ), 0 ).toInt() );
@@ -1254,7 +1254,7 @@ void QgsOptions::saveOptions()
   }
   mSettings->setValue( QStringLiteral( "/qgis/enableMacros" ), cmbEnableMacros->currentIndex() );
 
-  mSettings->setValue( QStringLiteral( "/qgis/nullValue" ), leNullValue->text() );
+  QgsApplication::setNullRepresentation( leNullValue->text() );
   mSettings->setValue( QStringLiteral( "/qgis/style" ), cmbStyle->currentText() );
   mSettings->setValue( QStringLiteral( "/IconSize" ), cmbIconSize->currentText() );
 
diff --git a/src/core/fieldformatter/qgsdatetimefieldformatter.cpp b/src/core/fieldformatter/qgsdatetimefieldformatter.cpp
index 3c793ca795c..a5333fd90b0 100644
--- a/src/core/fieldformatter/qgsdatetimefieldformatter.cpp
+++ b/src/core/fieldformatter/qgsdatetimefieldformatter.cpp
@@ -34,7 +34,7 @@ QString QgsDateTimeFieldFormatter::representValue( QgsVectorLayer* layer, int fi
   if ( value.isNull() )
   {
     QSettings settings;
-    return settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+    return QgsApplication::nullRepresentation();
   }
 
   const QgsField field = layer->fields().at( fieldIndex );
diff --git a/src/core/fieldformatter/qgskeyvaluefieldformatter.cpp b/src/core/fieldformatter/qgskeyvaluefieldformatter.cpp
index 06db8930205..3628a3acb95 100644
--- a/src/core/fieldformatter/qgskeyvaluefieldformatter.cpp
+++ b/src/core/fieldformatter/qgskeyvaluefieldformatter.cpp
@@ -14,6 +14,7 @@
  *                                                                         *
  ***************************************************************************/
 #include "qgskeyvaluefieldformatter.h"
+#include "qgsapplication.h"
 
 #include <QSettings>
 
@@ -32,7 +33,7 @@ QString QgsKeyValueFieldFormatter::representValue( QgsVectorLayer* layer, int fi
   if ( value.isNull() )
   {
     QSettings settings;
-    return settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+    return QgsApplication::nullRepresentation();
   }
 
   QString result;
diff --git a/src/core/fieldformatter/qgslistfieldformatter.cpp b/src/core/fieldformatter/qgslistfieldformatter.cpp
index 2a78be7c5ee..3214eb21464 100644
--- a/src/core/fieldformatter/qgslistfieldformatter.cpp
+++ b/src/core/fieldformatter/qgslistfieldformatter.cpp
@@ -14,7 +14,7 @@
  *                                                                         *
  ***************************************************************************/
 #include "qgslistfieldformatter.h"
-
+#include "qgsapplication.h"
 #include <QSettings>
 
 QString QgsListFieldFormatter::id() const
@@ -32,7 +32,7 @@ QString QgsListFieldFormatter::representValue( QgsVectorLayer* layer, int fieldI
   if ( value.isNull() )
   {
     QSettings settings;
-    return settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+    return QgsApplication::nullRepresentation();
   }
 
   QString result;
diff --git a/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp b/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
index d4f8ee28b44..4fdee0b3fc9 100644
--- a/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
+++ b/src/core/fieldformatter/qgsvaluerelationfieldformatter.cpp
@@ -47,7 +47,7 @@ QString QgsValueRelationFieldFormatter::representValue( QgsVectorLayer* layer, i
   Q_UNUSED( layer )
   Q_UNUSED( fieldIndex )
 
-  QgsValueRelationFieldFormatter::ValueRelationCache vrCache;
+  ValueRelationCache vrCache;
 
   if ( cache.isValid() )
   {
@@ -77,8 +77,7 @@ QString QgsValueRelationFieldFormatter::representValue( QgsVectorLayer* layer, i
   {
     if ( value.isNull() )
     {
-      QSettings settings;
-      return settings.value( "qgis/nullValue", "NULL" ).toString();
+      return QgsApplication::nullRepresentation();
     }
 
     Q_FOREACH ( const QgsValueRelationFieldFormatter::ValueRelationItem& item, vrCache )
diff --git a/src/core/qgsapplication.cpp b/src/core/qgsapplication.cpp
index b5d410888bc..8ff33afd6e6 100644
--- a/src/core/qgsapplication.cpp
+++ b/src/core/qgsapplication.cpp
@@ -1258,6 +1258,25 @@ void QgsApplication::copyPath( const QString& src, const QString& dst )
   }
 }
 
+QString QgsApplication::nullRepresentation()
+{
+  QgsApplication* app = instance();
+  if ( app->mNullRepresentation.isNull() )
+    app->mNullRepresentation = QSettings().value( QStringLiteral( "qgis/nullValue" ), QStringLiteral( "NULL" ) ).toString();
+  return app->mNullRepresentation;
+}
+
+void QgsApplication::setNullRepresentation( const QString& nullRepresentation )
+{
+  QgsApplication* app = instance();
+  if ( app->mNullRepresentation == nullRepresentation )
+    return;
+
+  app->mNullRepresentation = nullRepresentation;
+  QSettings().setValue( QStringLiteral( "qgis/nullValue" ), nullRepresentation );
+  emit app->nullRepresentationChanged();
+}
+
 QgsActionScopeRegistry* QgsApplication::actionScopeRegistry()
 {
   return instance()->mActionScopeRegistry;
diff --git a/src/core/qgsapplication.h b/src/core/qgsapplication.h
index 168e2df8e1b..c980f962265 100644
--- a/src/core/qgsapplication.h
+++ b/src/core/qgsapplication.h
@@ -402,6 +402,21 @@ class CORE_EXPORT QgsApplication : public QApplication
      */
     static QgsFieldFormatterRegistry* fieldKitRegistry();
 
+    /**
+     * This string is used to represent the value `NULL` throughout QGIS.
+     *
+     * In general, when passing values around, prefer to use a null QVariant
+     * `QVariant( field.type() )` or `QVariant( QVariant::Int )`. This value
+     * should only be used in the final presentation step when showing values
+     * in a widget or sending it to a web browser.
+     */
+    static QString nullRepresentation();
+
+    /**
+     * \copydoc nullRepresentation()
+     */
+    static void setNullRepresentation( const QString& nullRepresentation );
+
   public slots:
 
     /** Causes the application instance to emit the settingsChanged() signal. This should
@@ -422,6 +437,11 @@ class CORE_EXPORT QgsApplication : public QApplication
      */
     void settingsChanged();
 
+    /**
+     * \copydoc nullRepresentation()
+     */
+    void nullRepresentationChanged();
+
   private:
     static void copyPath( const QString& src, const QString& dst );
     static QObject* ABISYM( mFileOpenEventReceiver );
@@ -472,6 +492,7 @@ class CORE_EXPORT QgsApplication : public QApplication
     QgsRuntimeProfiler* mProfiler;
     QgsTaskManager* mTaskManager;
     QgsFieldFormatterRegistry* mFieldFormatterRegistry;
+    QString mNullRepresentation;
 };
 
 #endif
diff --git a/src/core/qgsfield.cpp b/src/core/qgsfield.cpp
index c60aa9dba24..5cfa7a633a1 100644
--- a/src/core/qgsfield.cpp
+++ b/src/core/qgsfield.cpp
@@ -211,7 +211,7 @@ QString QgsField::displayString( const QVariant& v ) const
   if ( v.isNull() )
   {
     QSettings settings;
-    return settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+    return QgsApplication::nullRepresentation();
   }
 
   if ( d->type == QVariant::Double && d->precision > 0 )
diff --git a/src/gui/attributetable/qgsfeaturelistmodel.cpp b/src/gui/attributetable/qgsfeaturelistmodel.cpp
index e33c2c5a75c..7ddcb1d9d47 100644
--- a/src/gui/attributetable/qgsfeaturelistmodel.cpp
+++ b/src/gui/attributetable/qgsfeaturelistmodel.cpp
@@ -73,7 +73,7 @@ QVariant QgsFeatureListModel::data( const QModelIndex &index, int role ) const
   {
     if ( role == Qt::DisplayRole )
     {
-      return QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+      return QgsApplication::nullRepresentation();
     }
     else if ( role == QgsAttributeTableModel::FeatureIdRole )
     {
diff --git a/src/gui/editorwidgets/qgsdatetimeedit.cpp b/src/gui/editorwidgets/qgsdatetimeedit.cpp
index 264d4e2be6d..bc028cdf4e9 100644
--- a/src/gui/editorwidgets/qgsdatetimeedit.cpp
+++ b/src/gui/editorwidgets/qgsdatetimeedit.cpp
@@ -37,7 +37,7 @@ QgsDateTimeEdit::QgsDateTimeEdit( QWidget *parent )
   mClearButton->hide();
   connect( mClearButton, SIGNAL( clicked() ), this, SLOT( clear() ) );
 
-  mNullLabel = new QLineEdit( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString(), this );
+  mNullLabel = new QLineEdit( QgsApplication::nullRepresentation(), this );
   mNullLabel->setReadOnly( true );
   mNullLabel->setStyleSheet( QStringLiteral( "position: absolute; border: none; font-style: italic; color: grey;" ) );
   mNullLabel->hide();
diff --git a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
index 6920f89a3b3..8ceb19221e9 100644
--- a/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsdefaultsearchwidgetwrapper.cpp
@@ -58,7 +58,7 @@ void QgsDefaultSearchWidgetWrapper::setExpression( QString exp )
   bool numeric = ( fldType == QVariant::Int || fldType == QVariant::Double || fldType == QVariant::LongLong );
 
   QSettings settings;
-  QString nullValue = settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+  QString nullValue = QgsApplication::nullRepresentation();
   QString fieldName = layer()->fields().at( mFieldIdx ).name();
   QString str;
   if ( exp == nullValue )
diff --git a/src/gui/editorwidgets/qgsexternalresourcewidgetwrapper.cpp b/src/gui/editorwidgets/qgsexternalresourcewidgetwrapper.cpp
index ccac4d02b8d..2a8db09ff4f 100644
--- a/src/gui/editorwidgets/qgsexternalresourcewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsexternalresourcewidgetwrapper.cpp
@@ -41,7 +41,7 @@ QVariant QgsExternalResourceWidgetWrapper::value() const
 
   if ( mLineEdit )
   {
-    if ( mLineEdit->text().isEmpty() || mLineEdit->text() == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( mLineEdit->text().isEmpty() || mLineEdit->text() == QgsApplication::nullRepresentation() )
     {
       return QVariant( field().type() );
     }
@@ -93,7 +93,7 @@ void QgsExternalResourceWidgetWrapper::initWidget( QWidget* editor )
     QgsFilterLineEdit* fle = qobject_cast<QgsFilterLineEdit*>( editor );
     if ( fle )
     {
-      fle->setNullValue( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      fle->setNullValue( QgsApplication::nullRepresentation() );
     }
   }
   else
@@ -151,7 +151,7 @@ void QgsExternalResourceWidgetWrapper::setValue( const QVariant& value )
   {
     if ( value.isNull() )
     {
-      mLineEdit->setText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mLineEdit->setText( QgsApplication::nullRepresentation() );
     }
     else
     {
@@ -169,7 +169,7 @@ void QgsExternalResourceWidgetWrapper::setValue( const QVariant& value )
   {
     if ( value.isNull() )
     {
-      mQgsWidget->setDocumentPath( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mQgsWidget->setDocumentPath( QgsApplication::nullRepresentation() );
     }
     else
     {
diff --git a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
index 55d8c0db5f3..32bc438d8b8 100644
--- a/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsfilenamewidgetwrapper.cpp
@@ -36,7 +36,7 @@ QVariant QgsFileNameWidgetWrapper::value() const
 
   if ( mLineEdit )
   {
-    if ( mLineEdit->text() == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( mLineEdit->text() == QgsApplication::nullRepresentation() )
       value = QVariant( field().type() );
     else
       value = mLineEdit->text();
@@ -103,7 +103,7 @@ void QgsFileNameWidgetWrapper::initWidget( QWidget* editor )
     QgsFilterLineEdit* fle = qobject_cast<QgsFilterLineEdit*>( editor );
     if ( fle )
     {
-      fle->setNullValue( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      fle->setNullValue( QgsApplication::nullRepresentation() );
     }
 
     connect( mLineEdit, SIGNAL( textChanged( QString ) ), this, SLOT( valueChanged( QString ) ) );
@@ -115,7 +115,7 @@ void QgsFileNameWidgetWrapper::setValue( const QVariant& value )
   if ( mLineEdit )
   {
     if ( value.isNull() )
-      mLineEdit->setText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mLineEdit->setText( QgsApplication::nullRepresentation() );
     else
       mLineEdit->setText( value.toString() );
   }
diff --git a/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp b/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
index fe4017ae8c8..5be3e1e3b98 100644
--- a/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsphotowidgetwrapper.cpp
@@ -137,7 +137,7 @@ QVariant QgsPhotoWidgetWrapper::value() const
 
   if ( mLineEdit )
   {
-    if ( mLineEdit->text() == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( mLineEdit->text() == QgsApplication::nullRepresentation() )
       v = QVariant( QVariant::String );
     else
       v = mLineEdit->text();
@@ -223,7 +223,7 @@ void QgsPhotoWidgetWrapper::initWidget( QWidget* editor )
     QgsFilterLineEdit *fle = qobject_cast<QgsFilterLineEdit*>( mLineEdit );
     if ( fle )
     {
-      fle->setNullValue( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      fle->setNullValue( QgsApplication::nullRepresentation() );
     }
 
     connect( mLineEdit, SIGNAL( textChanged( QString ) ), this, SLOT( valueChanged( QString ) ) );
@@ -246,7 +246,7 @@ void QgsPhotoWidgetWrapper::setValue( const QVariant& value )
   {
     if ( value.isNull() )
     {
-      whileBlocking( mLineEdit )->setText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      whileBlocking( mLineEdit )->setText( QgsApplication::nullRepresentation() );
       clearPicture();
     }
     else
diff --git a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
index 0d584fc7060..b3c3db1a135 100644
--- a/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrangewidgetwrapper.cpp
@@ -116,7 +116,7 @@ void QgsRangeWidgetWrapper::initWidget( QWidget* editor )
         minval -= stepval;
       }
       mDoubleSpinBox->setValue( minval );
-      mDoubleSpinBox->setSpecialValueText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mDoubleSpinBox->setSpecialValueText( QgsApplication::nullRepresentation() );
     }
     mDoubleSpinBox->setMinimum( min.isValid() ? min.toDouble() : std::numeric_limits<double>::min() );
     mDoubleSpinBox->setMaximum( max.isValid() ? max.toDouble() : std::numeric_limits<double>::max() );
@@ -137,7 +137,7 @@ void QgsRangeWidgetWrapper::initWidget( QWidget* editor )
       int stepval = step.toInt();
       minval -= stepval;
       mIntSpinBox->setValue( minval );
-      mIntSpinBox->setSpecialValueText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mIntSpinBox->setSpecialValueText( QgsApplication::nullRepresentation() );
     }
     setupIntEditor( min, max, step, mIntSpinBox, this );
     if ( config( QStringLiteral( "Suffix" ) ).isValid() )
diff --git a/src/gui/editorwidgets/qgsrelationreferencesearchwidgetwrapper.cpp b/src/gui/editorwidgets/qgsrelationreferencesearchwidgetwrapper.cpp
index 950baefbad2..a5cdafa84df 100644
--- a/src/gui/editorwidgets/qgsrelationreferencesearchwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrelationreferencesearchwidgetwrapper.cpp
@@ -137,7 +137,7 @@ void QgsRelationReferenceSearchWidgetWrapper::onValueChanged( const QVariant& va
   else
   {
     QSettings settings;
-    setExpression( value.isNull() ? settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() : value.toString() );
+    setExpression( value.isNull() ? QgsApplication::nullRepresentation() : value.toString() );
     emit valueChanged();
   }
   emit expressionChanged( mExpression );
@@ -146,7 +146,7 @@ void QgsRelationReferenceSearchWidgetWrapper::onValueChanged( const QVariant& va
 void QgsRelationReferenceSearchWidgetWrapper::setExpression( QString exp )
 {
   QSettings settings;
-  QString nullValue = settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+  QString nullValue = QgsApplication::nullRepresentation();
   QString fieldName = layer()->fields().at( mFieldIdx ).name();
 
   QString str;
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidget.cpp b/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
index 432959fa87b..c83c55c1793 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
+++ b/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
@@ -302,7 +302,7 @@ void QgsRelationReferenceWidget::setForeignKey( const QVariant& value )
 
 void QgsRelationReferenceWidget::deleteForeignKey()
 {
-  QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+  QVariant nullValue = QgsApplication::nullRepresentation();
   if ( mReadOnlySelector )
   {
     QString nullText = QLatin1String( "" );
@@ -477,7 +477,7 @@ void QgsRelationReferenceWidget::init()
         mFilterComboBoxes << cb;
         mReferencedLayer->uniqueValues( idx, uniqueValues );
         cb->addItem( mReferencedLayer->attributeDisplayName( idx ) );
-        QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+        QVariant nullValue = QgsApplication::nullRepresentation();
         cb->addItem( nullValue.toString(), QVariant( mReferencedLayer->fields().at( idx ).type() ) );
 
         qSort( uniqueValues.begin(), uniqueValues.end(), qgsVariantLessThan );
@@ -496,7 +496,7 @@ void QgsRelationReferenceWidget::init()
 
       if ( mChainFilters )
       {
-        QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+        QVariant nullValue = QgsApplication::nullRepresentation();
 
         QgsFeature ft;
         QgsFeatureIterator fit = layerCache->getFeatures();
@@ -552,7 +552,7 @@ void QgsRelationReferenceWidget::init()
     mComboBox->setCompleter( completer );
 
 
-    QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+    QVariant nullValue = QgsApplication::nullRepresentation();
 
     if ( mChainFilters && mFeature.isValid() )
     {
@@ -797,7 +797,7 @@ void QgsRelationReferenceWidget::mapToolDeactivated()
 
 void QgsRelationReferenceWidget::filterChanged()
 {
-  QVariant nullValue = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+  QVariant nullValue = QgsApplication::nullRepresentation();
 
   QStringList filters;
   QgsAttributeList attrs;
diff --git a/src/gui/editorwidgets/qgstexteditwrapper.cpp b/src/gui/editorwidgets/qgstexteditwrapper.cpp
index c5d4d7d8893..dea2534de38 100644
--- a/src/gui/editorwidgets/qgstexteditwrapper.cpp
+++ b/src/gui/editorwidgets/qgstexteditwrapper.cpp
@@ -56,7 +56,7 @@ QVariant QgsTextEditWrapper::value() const
   }
 
   if (( v.isEmpty() && ( field().type() == QVariant::Int || field().type() == QVariant::Double || field().type() == QVariant::LongLong || field().type() == QVariant::Date ) ) ||
-      v == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+      v == QgsApplication::nullRepresentation() )
     return QVariant( field().type() );
 
   if ( !defaultValue().isNull() && v == defaultValue().toString() )
@@ -119,7 +119,7 @@ void QgsTextEditWrapper::initWidget( QWidget* editor )
     QVariant defVal = defaultValue();
     if ( defVal.isNull() )
     {
-      defVal = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" );
+      defVal = QgsApplication::nullRepresentation();
     }
 
     QgsFilterLineEdit *fle = qobject_cast<QgsFilterLineEdit*>( mLineEdit );
@@ -215,7 +215,7 @@ void QgsTextEditWrapper::setWidgetValue( const QVariant& val )
   if ( val.isNull() )
   {
     if ( !( field().type() == QVariant::Int || field().type() == QVariant::Double || field().type() == QVariant::LongLong || field().type() == QVariant::Date ) )
-      v = QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+      v = QgsApplication::nullRepresentation();
   }
   else
     v = val.toString();
diff --git a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
index f1e9a55f7c8..88753907811 100644
--- a/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsuniquevaluewidgetwrapper.cpp
@@ -37,7 +37,7 @@ QVariant QgsUniqueValuesWidgetWrapper::value() const
 
   if ( mLineEdit )
   {
-    if ( mLineEdit->text() == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( mLineEdit->text() == QgsApplication::nullRepresentation() )
       value = QVariant( field().type() );
     else
       value = mLineEdit->text();
@@ -83,7 +83,7 @@ void QgsUniqueValuesWidgetWrapper::initWidget( QWidget* editor )
     QgsFilterLineEdit* fle = qobject_cast<QgsFilterLineEdit*>( editor );
     if ( fle && !( field().type() == QVariant::Int || field().type() == QVariant::Double || field().type() == QVariant::LongLong || field().type() == QVariant::Date ) )
     {
-      fle->setNullValue( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      fle->setNullValue( QgsApplication::nullRepresentation() );
     }
 
     QCompleter* c = new QCompleter( sValues );
@@ -127,7 +127,7 @@ void QgsUniqueValuesWidgetWrapper::setValue( const QVariant& value )
   if ( mLineEdit )
   {
     if ( value.isNull() )
-      mLineEdit->setText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mLineEdit->setText( QgsApplication::nullRepresentation() );
     else
       mLineEdit->setText( value.toString() );
   }
diff --git a/src/gui/editorwidgets/qgsvaluemapconfigdlg.cpp b/src/gui/editorwidgets/qgsvaluemapconfigdlg.cpp
index a9c76c137ab..d7d54c69860 100644
--- a/src/gui/editorwidgets/qgsvaluemapconfigdlg.cpp
+++ b/src/gui/editorwidgets/qgsvaluemapconfigdlg.cpp
@@ -17,6 +17,7 @@
 
 #include "qgsattributetypeloaddialog.h"
 #include "qgsvaluemapfieldformatter.h"
+#include "qgsapplication.h"
 
 #include <QSettings>
 #include <QFileDialog>
@@ -52,7 +53,7 @@ QVariantMap QgsValueMapConfigDlg::config()
       continue;
 
     QString ks = ki->text();
-    if (( ks == settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() ) && !( ki->flags() & Qt::ItemIsEditable ) )
+    if (( ks == QgsApplication::nullRepresentation() ) && !( ki->flags() & Qt::ItemIsEditable ) )
       ks = VALUEMAP_NULL_TEXT;
 
     if ( !vi || vi->text().isNull() )
@@ -159,7 +160,7 @@ void QgsValueMapConfigDlg::setRow( int row, const QString& value, const QString&
   {
     QFont cellFont;
     cellFont.setItalic( true );
-    valueCell = new QTableWidgetItem( settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+    valueCell = new QTableWidgetItem( QgsApplication::nullRepresentation() );
     valueCell->setFont( cellFont );
     valueCell->setFlags( Qt::ItemIsSelectable | Qt::ItemIsEnabled );
     descriptionCell->setFont( cellFont );
@@ -246,7 +247,7 @@ void QgsValueMapConfigDlg::loadFromCSVButtonPushed()
       val = val.mid( 1, val.length() - 2 );
     }
 
-    if ( key == settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( key == QgsApplication::nullRepresentation() )
       key = VALUEMAP_NULL_TEXT;
 
     map[ key ] = val;
diff --git a/src/gui/editorwidgets/qgsvaluerelationsearchwidgetwrapper.cpp b/src/gui/editorwidgets/qgsvaluerelationsearchwidgetwrapper.cpp
index 89ac128ad37..a9352983d04 100644
--- a/src/gui/editorwidgets/qgsvaluerelationsearchwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsvaluerelationsearchwidgetwrapper.cpp
@@ -190,7 +190,7 @@ void QgsValueRelationSearchWidgetWrapper::onValueChanged()
   else
   {
     QSettings settings;
-    setExpression( vl.isNull() ? settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() : vl.toString() );
+    setExpression( vl.isNull() ? QgsApplication::nullRepresentation() : vl.toString() );
     emit valueChanged();
   }
   emit expressionChanged( mExpression );
@@ -199,7 +199,7 @@ void QgsValueRelationSearchWidgetWrapper::onValueChanged()
 void QgsValueRelationSearchWidgetWrapper::setExpression( QString exp )
 {
   QSettings settings;
-  QString nullValue = settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+  QString nullValue = QgsApplication::nullRepresentation();
   QString fieldName = layer()->fields().at( mFieldIdx ).name();
 
   QString str;
diff --git a/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp b/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
index 58bcf3d7465..c0fac4d7d1d 100644
--- a/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgswebviewwidgetwrapper.cpp
@@ -48,7 +48,7 @@ QVariant QgsWebViewWidgetWrapper::value() const
 
   if ( mLineEdit )
   {
-    if ( mLineEdit->text() == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() )
+    if ( mLineEdit->text() == QgsApplication::nullRepresentation() )
       v = QVariant( QVariant::String );
     else
       v = mLineEdit->text();
@@ -101,7 +101,7 @@ void QgsWebViewWidgetWrapper::initWidget( QWidget* editor )
     QgsFilterLineEdit* fle = qobject_cast<QgsFilterLineEdit*>( mLineEdit );
     if ( fle )
     {
-      fle->setNullValue( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      fle->setNullValue( QgsApplication::nullRepresentation() );
     }
 
     container = qobject_cast<QWidget*>( mLineEdit->parent() );
@@ -151,7 +151,7 @@ void QgsWebViewWidgetWrapper::setValue( const QVariant& value )
   if ( mLineEdit )
   {
     if ( value.isNull() )
-      mLineEdit->setText( QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString() );
+      mLineEdit->setText( QgsApplication::nullRepresentation() );
     else
       mLineEdit->setText( value.toString() );
   }
diff --git a/src/gui/qgsfieldvalidator.cpp b/src/gui/qgsfieldvalidator.cpp
index 8c4eea9da80..a6b03cf914d 100644
--- a/src/gui/qgsfieldvalidator.cpp
+++ b/src/gui/qgsfieldvalidator.cpp
@@ -28,6 +28,7 @@
 #include "qgslogger.h"
 #include "qgslonglongvalidator.h"
 #include "qgsfields.h"
+#include "qgsapplication.h"
 
 QgsFieldValidator::QgsFieldValidator( QObject *parent, const QgsField &field, const QString& defaultValue, const QString& dateFormat )
     : QValidator( parent )
@@ -84,7 +85,7 @@ QgsFieldValidator::QgsFieldValidator( QObject *parent, const QgsField &field, co
   }
 
   QSettings settings;
-  mNullValue = settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+  mNullValue = QgsApplication::nullRepresentation();
 }
 
 QgsFieldValidator::~QgsFieldValidator()
diff --git a/src/gui/qgsfilewidget.cpp b/src/gui/qgsfilewidget.cpp
index ad22c4b9782..ad46fb2ae56 100644
--- a/src/gui/qgsfilewidget.cpp
+++ b/src/gui/qgsfilewidget.cpp
@@ -27,6 +27,7 @@
 #include "qgsfilterlineedit.h"
 #include "qgslogger.h"
 #include "qgsproject.h"
+#include "qgsapplication.h"
 
 QgsFileWidget::QgsFileWidget( QWidget *parent )
     : QWidget( parent )
@@ -82,7 +83,7 @@ QString QgsFileWidget::filePath()
 
 void QgsFileWidget::setFilePath( QString path )
 {
-  if ( path == QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ) )
+  if ( path == QgsApplication::nullRepresentation() )
   {
     path = QLatin1String( "" );
   }
@@ -286,7 +287,7 @@ QString QgsFileWidget::toUrl( const QString& path ) const
   QString rep;
   if ( path.isEmpty() )
   {
-    return QSettings().value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+    return QgsApplication::nullRepresentation();
   }
 
   QString urlStr = relativePath( path, false );
diff --git a/src/gui/qgsquerybuilder.cpp b/src/gui/qgsquerybuilder.cpp
index 384b4a3c2cd..2f80d422abd 100644
--- a/src/gui/qgsquerybuilder.cpp
+++ b/src/gui/qgsquerybuilder.cpp
@@ -120,7 +120,7 @@ void QgsQueryBuilder::fillValues( int idx, int limit )
   mLayer->uniqueValues( idx, values, limit );
 
   QSettings settings;
-  QString nullValue = settings.value( QStringLiteral( "qgis/nullValue" ), "NULL" ).toString();
+  QString nullValue = QgsApplication::nullRepresentation();
 
   QgsDebugMsg( QString( "nullValue: %1" ).arg( nullValue ) );
 
diff --git a/tests/src/core/CMakeLists.txt b/tests/src/core/CMakeLists.txt
index 68d93bdd22f..d6c310b3242 100644
--- a/tests/src/core/CMakeLists.txt
+++ b/tests/src/core/CMakeLists.txt
@@ -15,6 +15,7 @@ INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}
   ${CMAKE_SOURCE_DIR}/src/core/layertree
   ${CMAKE_SOURCE_DIR}/src/core/raster
   ${CMAKE_SOURCE_DIR}/src/core/symbology-ng
+  ${CMAKE_SOURCE_DIR}/src/test
 )
 INCLUDE_DIRECTORIES(SYSTEM
   ${QT_INCLUDE_DIR}
diff --git a/tests/src/core/testqgsfield.cpp b/tests/src/core/testqgsfield.cpp
index 3d01641e18d..60d846e22dd 100644
--- a/tests/src/core/testqgsfield.cpp
+++ b/tests/src/core/testqgsfield.cpp
@@ -20,6 +20,8 @@
 #include <QSharedPointer>
 
 #include "qgsfield.h"
+#include "qgsapplication.h"
+#include "qgstest.h"
 
 class TestQgsField: public QObject
 {
@@ -299,8 +301,7 @@ void TestQgsField::displayString()
   QCOMPARE( stringField.displayString( test ), test );
 
   //test NULL
-  QSettings s;
-  s.setValue( QStringLiteral( "qgis/nullValue" ), "TEST NULL" );
+  QgsApplication::setNullRepresentation( "TEST NULL" );
   QVariant nullString = QVariant( QVariant::String );
   QCOMPARE( stringField.displayString( nullString ), QString( "TEST NULL" ) );
 
@@ -513,5 +514,5 @@ void TestQgsField::collection()
   QVERIFY( !field.convertCompatible( str ) );
 }
 
-QTEST_MAIN( TestQgsField )
+QGSTEST_MAIN( TestQgsField )
 #include "testqgsfield.moc"