diff -up gdl-0.9.4/src/pythongdl.cpp.python gdl-0.9.4/src/pythongdl.cpp
--- gdl-0.9.4/src/pythongdl.cpp.python	2013-07-26 03:30:32.000000000 -0600
+++ gdl-0.9.4/src/pythongdl.cpp	2013-09-30 10:24:27.092666180 -0600
@@ -373,7 +373,7 @@ PyObject *GDLSub( PyObject *self, PyObje
     if( libCall)
       e = new EnvT( NULL, sub);
     else
-      e = new EnvUDT( NULL, sub);
+      e = new EnvUDT( NULL, static_cast<DSubUD*>(sub));
 
     Guard< EnvBaseT> e_guard( e);