The fix I suggested for this resolved CLIM Listener bug: Package lock errors when compiling/loading with CMUCL 19 or later http://mcclim.cliki.net/Bug#listener-cmucl-package-lock was shortsighted. I conditionalized package locking on feature cmu19a: #+cmu19a (progn (setf (ext:package-definition-lock (find-package "DEBUG")) nil) (setf (ext:package-definition-lock (find-package "COMMON-LISP")) nil) (setf (ext:package-definition-lock (find-package "EXT")) nil)) But compilation and loading of the Listener fail again with CMUCL Snapshot (19B) 2005-06, which is the first in the 19b series. A short term fix may be to conditionalize on just cmu19. Paolo -- Lisp Propulsion Laboratory log - http://www.paoloamoroso.it/log