diff -Naur Persistence-2.13.1/src/Persistence/_Persistence.c Persistence-2.13.1.new/src/Persistence/_Persistence.c
--- Persistence-2.13.1/src/Persistence/_Persistence.c	2010-04-07 18:39:12.000000000 +0800
+++ Persistence-2.13.1.new/src/Persistence/_Persistence.c	2010-06-14 21:01:05.494522968 +0800
@@ -160,6 +160,7 @@
   if (Ptype.tp_bases == NULL)
     return;
   Ptype.tp_base = cPersistenceCAPI->pertype;
+  Ptype.tp_basicsize = cPersistenceCAPI->pertype->tp_basicsize;
   
   Ptype.ob_type = ECExtensionClassType;
   if (PyType_Ready(&Ptype) < 0)
diff -Naur Persistence-2.13.1/src/Persistence.egg-info/PKG-INFO Persistence-2.13.1.new/src/Persistence.egg-info/PKG-INFO