For more reliable operation of 60.57 under MCL, I recommmend that you replace your version of http:mac;server;tcp-stream.lisp with http://wilson.ai.mit.edu/cl-http/sources/mac/tcp-stream.lisp The changed definition is #+:ccl-3 (stream-tyo ((s modal-ascii-or-binary-tcp-stream-mixin) char) It eliminates a bug whereby the mac heap could be corrupted under certain infrequent circumstances.