Index: src/java/com/thoughtworks/xstream/converters/reflection/CGLIBEnhancedConverter.java
===================================================================
--- src/java/com/thoughtworks/xstream/converters/reflection/CGLIBEnhancedConverter.java	(revision 1698)
+++ src/java/com/thoughtworks/xstream/converters/reflection/CGLIBEnhancedConverter.java	(working copy)
@@ -173,7 +173,9 @@
             try {
                 Field field = (Field)fields.get(i);
                 Object callback = field.get(source);
-                list.add(callback);
+                if (callback != null) {
+            		list.add(callback);
+                }
             } catch (IllegalAccessException e) {
                 throw new ObjectAccessException("Access to "
                     + type.getName()