dev-lisp/clisp-2.49.92-r1 does this: if use hyperspec; then CLHSROOT="file:///${EPREFIX}/usr/share/doc/hyperspec/HyperSpec/" else CLHSROOT="http://www.lispworks.com/reference/HyperSpec/" fi but dev-lisp/hyperspec installs /usr/share/hyperspec/ as the version-independent symlink. so the ebuild should elide "doc/" from CLHSROOT. also http://www.lispworks.com/reference/HyperSpec/ redirects to an https url which clisp does not support. try running something like: (describe 'sqrt) in clisp w/o hyperspec in use too see the error. lastly, file:///${EPREFIX}/ has more slashes than it needs. EPREFIX should start with one if it is not empty, so file:/${EPREFIX}/ ought to work; in any case ://$ should always be enough.