Index: /applications/editors/josm/plugins/navigator/src/at/dallermassl/josm/plugin/navigator/NavigatorPlugin.java
===================================================================
--- /applications/editors/josm/plugins/navigator/src/at/dallermassl/josm/plugin/navigator/NavigatorPlugin.java	(revision 3765)
+++ /applications/editors/josm/plugins/navigator/src/at/dallermassl/josm/plugin/navigator/NavigatorPlugin.java	(revision 3766)
@@ -63,7 +63,9 @@
      */
     @Override
-    public void mapFrameInitialized(MapFrame oldFrame, MapFrame newFrame) {    
-        newFrame.toolBarActions.add(
-            new IconToggleButton(new NavigatorModeAction(newFrame, navigatorModel, navigatorLayer)));
+    public void mapFrameInitialized(MapFrame oldFrame, MapFrame newFrame) {
+        if(newFrame != null) {
+            newFrame.toolBarActions.add(
+                new IconToggleButton(new NavigatorModeAction(newFrame, navigatorModel, navigatorLayer)));
+        }
     }