I was recently somewhat burned (performance-wise) by clim-lisp:defconstant being really a defvar. Would something like the following be an acceptable substitute? It remains portable, but allows implementations to do a much better job for important cases like numeric constants: (defmacro clim-lisp-patch:defconstant (symbol value &optional docu) (if (typep value '(or number character)) `(cl:defconstant ,symbol ,value ,@(and docu (list docu))) `(defvar ,symbol ,value ,@(and docu (list docu))))) Cheers, -- Nikodemus