Index: pyyaml/trunk/lib/yaml/representer.py
===================================================================
--- pyyaml/trunk/lib/yaml/representer.py	(revision 173)
+++ pyyaml/trunk/lib/yaml/representer.py	(revision 206)
@@ -418,5 +418,5 @@
         cls = type(data)
         if cls in copy_reg.dispatch_table:
-            reduce = copy_reg.dispatch_table[cls]
+            reduce = copy_reg.dispatch_table[cls](data)
         elif hasattr(data, '__reduce_ex__'):
             reduce = data.__reduce_ex__(2)