Index: src/org/openstreetmap/josm/gui/layer/TMSLayer.java
===================================================================
--- src/org/openstreetmap/josm/gui/layer/TMSLayer.java	(revision 4412)
+++ src/org/openstreetmap/josm/gui/layer/TMSLayer.java	(working copy)
@@ -496,7 +496,7 @@
                                 } catch (URISyntaxException e1) {
                                     e1.printStackTrace();
                                 }
-                            } else if(attrToUBounds.contains(e.getPoint())) {
+                            } else if(attrToUBounds != null && attrToUBounds.contains(e.getPoint())) {
                                 try {
                                     java.awt.Desktop desktop = java.awt.Desktop.getDesktop();
                                     desktop.browse(new URI(tileSource.getTermsOfUseURL()));