Index: trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 9941)
+++ trunk/src/org/openstreetmap/josm/gui/history/HistoryBrowserModel.java	(revision 9942)
@@ -710,4 +710,6 @@
     @Override
     public void dataChanged(DataChangedEvent event) {
+        if (history == null)
+            return;
         OsmPrimitive primitive = event.getDataset().getPrimitiveById(history.getId(), history.getType());
         HistoryOsmPrimitive latest;