Index: /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 2792)
+++ /trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 2793)
@@ -108,5 +108,7 @@
         createPolygons(innerWays, innerPolygons);
         createPolygons(outerWays, outerPolygons);
-        addInnerToOuters();
+        if (!outerPolygons.isEmpty()) {
+            addInnerToOuters();
+        }
     }