Index: trunk/src/org/openstreetmap/josm/gui/MapView.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MapView.java	(revision 17444)
+++ trunk/src/org/openstreetmap/josm/gui/MapView.java	(revision 17445)
@@ -398,4 +398,6 @@
         layer.removePropertyChangeListener(this);
         invalidatedListener.removeFrom(layer);
+        if(layer == getNativeScaleLayer())
+            setNativeScaleLayer(null);
         layer.destroy();
         AudioPlayer.reset();