diff --git a/lib/yaml/representer.py b/lib/yaml/representer.py
index 932dede..2516813 100644
--- a/lib/yaml/representer.py
+++ b/lib/yaml/representer.py
@@ -417,7 +417,7 @@
 
         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)
         elif hasattr(data, '__reduce__'):