I know this is somewhat obscure but it nonetheless appears to be a bug: % package require XOTcl 1.3 % xotcl::Object ob ::ob % ob class xotcl::Class % ob info class Bus error (On Mac OS X 10.3.7) I was interested to find out if it's possible to make an already existing object into a class dynamically :-) (Should it be?) / http://www.fishpool.com/~setok/