diff --git a/src/core/drawingcanvas.cpp b/src/core/drawingcanvas.cpp
index e628c40f78..2e425fe6c6 100644
--- a/src/core/drawingcanvas.cpp
+++ b/src/core/drawingcanvas.cpp
@@ -271,7 +271,7 @@ void DrawingCanvas::strokeEnd( const QPointF &point )
   update();
 }
 
-void DrawingCanvas::drawStroke( QPainter *painter, const Stroke &stroke, bool onCanvas )
+void DrawingCanvas::drawStroke( QPainter *painter, const Stroke &stroke, bool onCanvas ) const
 {
   QPainterPath path( onCanvas ? stroke.points.at( 0 ) : canvasToItem( stroke.points.at( 0 ) ) );
   for ( int i = 1; i < stroke.points.size(); i++ )
@@ -310,7 +310,7 @@ void DrawingCanvas::undo()
   }
 }
 
-QPointF DrawingCanvas::itemToCanvas( const QPointF &point )
+QPointF DrawingCanvas::itemToCanvas( const QPointF &point ) const
 {
   const QPointF canvasTopLeft( size().width() / 2 - ( mBackgroundImage.size().width() * mZoomFactor / 2 ) + mOffset.x(),
                                size().height() / 2 - ( mBackgroundImage.size().height() * mZoomFactor / 2 ) + mOffset.y() );
@@ -318,7 +318,7 @@ QPointF DrawingCanvas::itemToCanvas( const QPointF &point )
                   ( point.y() - canvasTopLeft.y() ) / mZoomFactor );
 }
 
-QPointF DrawingCanvas::canvasToItem( const QPointF &point )
+QPointF DrawingCanvas::canvasToItem( const QPointF &point ) const
 {
   const QPointF canvasTopLeft( size().width() / 2 - ( mBackgroundImage.size().width() * mZoomFactor / 2 ) + mOffset.x(),
                                size().height() / 2 - ( mBackgroundImage.size().height() * mZoomFactor / 2 ) + mOffset.y() );
diff --git a/src/core/drawingcanvas.h b/src/core/drawingcanvas.h
index a4060a91e4..3268b5f7bc 100644
--- a/src/core/drawingcanvas.h
+++ b/src/core/drawingcanvas.h
@@ -174,10 +174,10 @@ class DrawingCanvas : public QQuickPaintedItem
         QList<QPointF> points;
     };
 
-    void drawStroke( QPainter *painter, const Stroke &stroke, bool onCanvas = true );
+    void drawStroke( QPainter *painter, const Stroke &stroke, bool onCanvas = true ) const;
 
-    QPointF itemToCanvas( const QPointF &point );
-    QPointF canvasToItem( const QPointF &point );
+    QPointF itemToCanvas( const QPointF &point ) const;
+    QPointF canvasToItem( const QPointF &point ) const;
 
     bool mIsEmpty = true;
     bool mIsDirty = false;