Index: trunk/src/org/openstreetmap/josm/gui/dialogs/layer/DuplicateAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/dialogs/layer/DuplicateAction.java	(revision 11503)
+++ trunk/src/org/openstreetmap/josm/gui/dialogs/layer/DuplicateAction.java	(revision 11505)
@@ -71,5 +71,5 @@
     public void updateEnabledState() {
         if (layer == null) {
-            if (model.getSelectedLayers().size() == 1) {
+            if (model != null && model.getSelectedLayers().size() == 1) {
                 setEnabled(model.getSelectedLayers().get(0) instanceof OsmDataLayer);
             } else {