I fixed a typo in port.lisp that caused an error during compiling under ACL. If you compile CM in ACL on linux or windows please refetch one of the following: Sources : ftp://ccrma-ftp.stanford.edu/pub/Lisp/cm/sources/cm-2.3.3.tar.gz ftp://ccrma-ftp.stanford.edu/pub/Lisp/cm/sources/cm-2.3.3.zip I updated the mac and binary archives as well but there is no need to refetch if you use these.