--- src/speaker.h.orig	2009-12-10 22:20:47.000000000 -0400
+++ src/speaker.h	2013-03-02 17:58:51.781035990 -0400
@@ -28,6 +28,7 @@
 class SpeakerItem : public QObject, public QGraphicsItem
 {
 	Q_OBJECT
+    Q_INTERFACES(QGraphicsItem)
 
 	private:
 	double radius;