Index: /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/MultipolygonCache.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/MultipolygonCache.java	(revision 4635)
+++ /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/MultipolygonCache.java	(revision 4636)
@@ -174,9 +174,11 @@
         for (Map<Relation, Multipolygon> map : maps) {
             Multipolygon m = map.get(r);
-            for (PolyData pd : m.getCombinedPolygons()) {
-                if (event instanceof NodeMovedEvent) {
-                    pd.nodeMoved((NodeMovedEvent) event);
-                } else if (event instanceof WayNodesChangedEvent) {
-                    pd.wayNodesChanged((WayNodesChangedEvent)event);
+            if (m != null) {
+                for (PolyData pd : m.getCombinedPolygons()) {
+                    if (event instanceof NodeMovedEvent) {
+                        pd.nodeMoved((NodeMovedEvent) event);
+                    } else if (event instanceof WayNodesChangedEvent) {
+                        pd.wayNodesChanged((WayNodesChangedEvent)event);
+                    }
                 }
             }