Index: trunk/src/org/openstreetmap/josm/plugins/PluginSelection.java
===================================================================
--- trunk/src/org/openstreetmap/josm/plugins/PluginSelection.java	(revision 1738)
+++ trunk/src/org/openstreetmap/josm/plugins/PluginSelection.java	(revision 1739)
@@ -95,5 +95,5 @@
     public boolean finish() {
         Collection<PluginInformation> toDownload = new LinkedList<PluginInformation>();
-        Collection<String> installedPlugins = Main.pref.getCollection("plugins", null);
+        Collection<String> installedPlugins = Main.pref.getCollection("plugins", Collections.<String>emptySet());
 
         String msg = "";