Index: trunk/src/org/openstreetmap/josm/gui/preferences/display/GPXSettingsPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/display/GPXSettingsPanel.java	(revision 17996)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/display/GPXSettingsPanel.java	(revision 17997)
@@ -251,5 +251,5 @@
      */
     public static void putLayerPrefLocal(GpxLayer layer, String key, String value) {
-        if (layer == null) return;
+        if (layer == null || layer.data == null) return;
         putLayerPrefLocal(layer.data, key, value);
     }