diff --git a/src/app/main.cpp b/src/app/main.cpp
index 6b671995f92..d2c699dda20 100644
--- a/src/app/main.cpp
+++ b/src/app/main.cpp
@@ -1126,7 +1126,7 @@ int main( int argc, char *argv[] )
         break;
       }
 
-      coords[i] = QString( myInitialExtent.mid( posOld, pos - posOld ) ).toDouble( &ok );
+      coords[i] = myInitialExtent.midRef( posOld, pos - posOld ).toDouble( &ok );
       if ( !ok )
         break;
 
@@ -1135,7 +1135,7 @@ int main( int argc, char *argv[] )
 
     // parse last coordinate
     if ( ok )
-      coords[3] = QString( myInitialExtent.mid( posOld ) ).toDouble( &ok );
+      coords[3] = myInitialExtent.midRef( posOld ).toDouble( &ok );
 
     if ( !ok )
     {
diff --git a/src/app/qgsprojectproperties.cpp b/src/app/qgsprojectproperties.cpp
index ec284d07854..e29170464be 100644
--- a/src/app/qgsprojectproperties.cpp
+++ b/src/app/qgsprojectproperties.cpp
@@ -1908,14 +1908,14 @@ void QgsProjectProperties::populateEllipsoidList()
       // Crash if no column?
       para1 = ( const char * )sqlite3_column_text( myPreparedStatement, 2 );
       para2 = ( const char * )sqlite3_column_text( myPreparedStatement, 3 );
-      myItem.semiMajor = para1.mid( 2 ).toDouble();
+      myItem.semiMajor = para1.midRef( 2 ).toDouble();
       if ( para2.left( 2 ) == "b=" )
       {
-        myItem.semiMinor = para2.mid( 2 ).toDouble();
+        myItem.semiMinor = para2.midRef( 2 ).toDouble();
       }
       else if ( para2.left( 3 ) == "rf=" )
       {
-        double invFlattening = para2.mid( 3 ).toDouble();
+        double invFlattening = para2.midRef( 3 ).toDouble();
         if ( invFlattening != 0.0 )
         {
           myItem.semiMinor = myItem.semiMajor - ( myItem.semiMajor / invFlattening );
diff --git a/src/core/qgscolorramp.cpp b/src/core/qgscolorramp.cpp
index 8442df2e777..73e9d44e2d3 100644
--- a/src/core/qgscolorramp.cpp
+++ b/src/core/qgscolorramp.cpp
@@ -72,7 +72,7 @@ QgsColorRamp* QgsGradientColorRamp::create( const QgsStringMap& props )
         continue;
 
       QColor c = QgsSymbolLayerUtils::decodeColor( stop.mid( i + 1 ) );
-      stops.append( QgsGradientStop( stop.left( i ).toDouble(), c ) );
+      stops.append( QgsGradientStop( stop.leftRef( i ).toDouble(), c ) );
     }
   }
 
diff --git a/src/core/qgscoordinatereferencesystem.cpp b/src/core/qgscoordinatereferencesystem.cpp
index a6822eede8a..dbac9726c63 100644
--- a/src/core/qgscoordinatereferencesystem.cpp
+++ b/src/core/qgscoordinatereferencesystem.cpp
@@ -500,7 +500,7 @@ bool QgsCoordinateReferenceSystem::hasAxisInverted() const
     {
       OGRSpatialReferenceH crs = OSRNewSpatialReference( nullptr );
 
-      if ( OSRImportFromEPSGA( crs, d->mAuthId.mid( 5 ).toInt() ) == OGRERR_NONE )
+      if ( OSRImportFromEPSGA( crs, d->mAuthId.midRef( 5 ).toInt() ) == OGRERR_NONE )
       {
         OSRGetAxis( crs, OSRIsGeographic( crs ) ? "GEOGCS" : "PROJCS", 0, &orientation );
       }
@@ -1750,7 +1750,7 @@ bool QgsCoordinateReferenceSystem::loadWkts( QHash<int, QString> &wkts, const ch
         return false;
 
       bool ok;
-      int epsg = line.left( pos ).toInt( &ok );
+      int epsg = line.leftRef( pos ).toInt( &ok );
       if ( !ok )
         return false;
 
@@ -1791,7 +1791,7 @@ bool QgsCoordinateReferenceSystem::loadIds( QHash<int, QString> &wkts )
         continue;
 
       bool ok;
-      int epsg = line.left( pos ).toInt( &ok );
+      int epsg = line.leftRef( pos ).toInt( &ok );
       if ( !ok )
         continue;
 
diff --git a/src/core/qgsdistancearea.cpp b/src/core/qgsdistancearea.cpp
index eb06b082454..6dd88dbf045 100644
--- a/src/core/qgsdistancearea.cpp
+++ b/src/core/qgsdistancearea.cpp
@@ -191,7 +191,7 @@ bool QgsDistanceArea::setEllipsoid( const QString& ellipsoid )
 
   // get major semiaxis
   if ( radius.left( 2 ) == "a=" )
-    mSemiMajor = radius.mid( 2 ).toDouble();
+    mSemiMajor = radius.midRef( 2 ).toDouble();
   else
   {
     QgsDebugMsg( QString( "setEllipsoid: wrong format of radius field: '%1'" ).arg( radius ) );
@@ -203,12 +203,12 @@ bool QgsDistanceArea::setEllipsoid( const QString& ellipsoid )
   // second one must be computed using formula: invf = a/(a-b)
   if ( parameter2.left( 2 ) == "b=" )
   {
-    mSemiMinor = parameter2.mid( 2 ).toDouble();
+    mSemiMinor = parameter2.midRef( 2 ).toDouble();
     mInvFlattening = mSemiMajor / ( mSemiMajor - mSemiMinor );
   }
   else if ( parameter2.left( 3 ) == "rf=" )
   {
-    mInvFlattening = parameter2.mid( 3 ).toDouble();
+    mInvFlattening = parameter2.midRef( 3 ).toDouble();
     mSemiMinor = mSemiMajor - ( mSemiMajor / mInvFlattening );
   }
   else
diff --git a/src/core/qgsogcutils.cpp b/src/core/qgsogcutils.cpp
index 693cae80ae0..6b8e69473da 100644
--- a/src/core/qgsogcutils.cpp
+++ b/src/core/qgsogcutils.cpp
@@ -2910,7 +2910,7 @@ QDomElement QgsOgcUtilsSQLStatementToFilter::toOgcFilter( const QgsSQLStatement:
 static QString mapBinarySpatialToOgc( const QString& name )
 {
   QString nameCompare( name );
-  if ( name.size() > 3 && name.mid( 0, 3 ).compare( "ST_", Qt::CaseInsensitive ) == 0 )
+  if ( name.size() > 3 && name.midRef( 0, 3 ).compare( "ST_", Qt::CaseInsensitive ) == 0 )
     nameCompare = name.mid( 3 );
   QStringList spatialOps;
   spatialOps << "BBOX" << "Intersects" << "Contains" << "Crosses" << "Equals"
@@ -2926,7 +2926,7 @@ static QString mapBinarySpatialToOgc( const QString& name )
 static QString mapTernarySpatialToOgc( const QString& name )
 {
   QString nameCompare( name );
-  if ( name.size() > 3 && name.mid( 0, 3 ).compare( "ST_", Qt::CaseInsensitive ) == 0 )
+  if ( name.size() > 3 && name.midRef( 0, 3 ).compare( "ST_", Qt::CaseInsensitive ) == 0 )
     nameCompare = name.mid( 3 );
   if ( nameCompare.compare( "DWithin", Qt::CaseInsensitive ) == 0 )
     return "DWithin";
diff --git a/src/plugins/georeferencer/qgsgeorefvalidators.cpp b/src/plugins/georeferencer/qgsgeorefvalidators.cpp
index 4202699009a..3cba8a33d1d 100644
--- a/src/plugins/georeferencer/qgsgeorefvalidators.cpp
+++ b/src/plugins/georeferencer/qgsgeorefvalidators.cpp
@@ -57,7 +57,7 @@ QValidator::State QgsDMSAndDDValidator::validate( QString &input, int &pos ) con
       rx.setPattern( "-?\\d{1,3}\\s60" );
       if ( rx.exactMatch( input ) )
       {
-        int in = input.left( input.indexOf( ' ' ) ).toInt();
+        int in = input.leftRef( input.indexOf( ' ' ) ).toInt();
         int grad =  input.startsWith( '-' ) ? in - 1 : in + 1;
         if ( grad <= 180 )
           input = QString::number( grad );
diff --git a/src/providers/grass/qgsgrassprovider.cpp b/src/providers/grass/qgsgrassprovider.cpp
index 31e59309c1e..421811e158e 100644
--- a/src/providers/grass/qgsgrassprovider.cpp
+++ b/src/providers/grass/qgsgrassprovider.cpp
@@ -525,7 +525,7 @@ int QgsGrassProvider::grassLayer( QString name )
     return -1;
   }
 
-  return name.left( pos ).toInt();
+  return name.leftRef( pos ).toInt();
 }
 
 int QgsGrassProvider::grassLayerType( QString name )
diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
index ef01dae574e..f413da09994 100644
--- a/src/providers/postgres/qgspostgresprovider.cpp
+++ b/src/providers/postgres/qgspostgresprovider.cpp
@@ -3852,7 +3852,7 @@ static QString getNextString( const QString& txt, int& i, const QString& sep )
     }
     i += stringRe.cap( 1 ).length() + 2;
     jumpSpace( txt, i );
-    if ( !txt.mid( i ).startsWith( sep ) && i < txt.length() )
+    if ( !txt.midRef( i ).startsWith( sep ) && i < txt.length() )
     {
       QgsLogger::warning( "Cannot find separator: " + txt.mid( i ) );
       return QString::null;
diff --git a/tests/bench/main.cpp b/tests/bench/main.cpp
index 83440169a7a..a1c542a1c75 100644
--- a/tests/bench/main.cpp
+++ b/tests/bench/main.cpp
@@ -557,7 +557,7 @@ int main( int argc, char *argv[] )
         break;
       }
 
-      coords[i] = QString( myInitialExtent.mid( posOld, pos - posOld ) ).toDouble( &ok );
+      coords[i] = myInitialExtent.midRef( posOld, pos - posOld ).toDouble( &ok );
       if ( !ok )
         break;
 
@@ -566,7 +566,7 @@ int main( int argc, char *argv[] )
 
     // parse last coordinate
     if ( ok )
-      coords[3] = QString( myInitialExtent.mid( posOld ) ).toDouble( &ok );
+      coords[3] = myInitialExtent.midRef( posOld ).toDouble( &ok );
 
     if ( !ok )
     {