Without the first patch, this answers nil: (build-declarations nil (filter-declaration-env (parse-declarations '((declare (fixnum x y z)))) :affecting '(x))) With it I get ((type fixnum x)) as I expect. A potential accuracy improvement for non-built-in types would be to use: #+clozure (ccl::specifier-type symbol env) similarly to the #+sbcl case; I will send that along as well if you like. Also a tiny typo in the comment is patched. -- I write stuff at http://failex.blogspot.com/ now. But the post formatter and themes are terrible for sharing code, the primary content, so it might go away sooner or later.