marshal_write_object() is empty in Python/asdl.c. The only use is in Python/Python-ast.c for writing a Number: case Num_kind: marshal_write_int(buf, off, 10); marshal_write_object(buf, off, o->v.Num.n); break; Not sure what needs to be done here. Do we need to handle arch sized ints? (ie 4 or 8 bytes). If not, couldn't we just use marshal_write_int? Neal