Index: trunk/src/org/openstreetmap/josm/gui/preferences/AddWMSLayerPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/AddWMSLayerPanel.java	(revision 4593)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/AddWMSLayerPanel.java	(revision 4594)
@@ -509,5 +509,5 @@
         if (ImageryType.TMS.equals(info.getImageryType())) {
             TMSLayer.checkUrl(info.getUrl());
-        } else {
+        } else if (selectedLayers != null) {
             HashSet<String> proj = new HashSet<String>();
             for(LayerDetails l : selectedLayers)