Index: trunk/src/org/openstreetmap/josm/actions/OpenFileAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/OpenFileAction.java	(revision 8704)
+++ trunk/src/org/openstreetmap/josm/actions/OpenFileAction.java	(revision 8705)
@@ -110,5 +110,5 @@
                 if (file.exists()) {
                     this.files.add(file);
-                } else {
+                } else if (file.getParentFile() != null) {
                     // try to guess an extension using the specified fileFilter
                     final File[] matchingFiles = file.getParentFile().listFiles(new FilenameFilter() {