diff --git a/python/core/symbology-ng-core.sip b/python/core/symbology-ng-core.sip
index 45ece6fa0400..e726f742aae5 100644
--- a/python/core/symbology-ng-core.sip
+++ b/python/core/symbology-ng-core.sip
@@ -453,7 +453,7 @@ class QgsSymbolV2RenderContext
 %End
 
     public:
-    QgsSymbolV2RenderContext( QgsRenderContext& c, QgsSymbolV2::OutputUnit u);
+    QgsSymbolV2RenderContext( QgsRenderContext& c, QgsSymbolV2::OutputUnit u , qreal alpha = 1.0 );
     ~QgsSymbolV2RenderContext();
 
     QgsRenderContext& renderContext();
@@ -462,6 +462,9 @@ class QgsSymbolV2RenderContext
     QgsSymbolV2::OutputUnit outputUnit() const;
     void setOutputUnit( QgsSymbolV2::OutputUnit u );
 
+    qreal alpha() const;
+    void setAlpha( qreal alpha );
+
     double outputLineWidth(double width) const;
     double outputPixelSize(double size) const;
 };