Index: trunk/src/org/openstreetmap/josm/data/imagery/LayerDetails.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/imagery/LayerDetails.java	(revision 13869)
+++ trunk/src/org/openstreetmap/josm/data/imagery/LayerDetails.java	(revision 13870)
@@ -117,5 +117,5 @@
      */
     public void addStyle(String name, String title) {
-        this.styles.put(name, title);
+        this.styles.put(name, title == null ? "" : title);
     }