@vertigo With quicklisp (and the quicklisp distribution) all the systems are built against each other each month and are all compatible with one another within one release. Most systems and their protocols stay the same so it's seen as much less of a priority by the community to solve this problem (granted it's not sustainable but this at the moment for the large part it isn't an issue)

There is qlot https://github.com/fukamachi/qlot if you need to freeze dependencies or pull in things that aren't in quicklisp. Although I haven't needed to use this myself

If you need help with anything else I would recommend asking questions in #lisp or #clschool on freenode, they're sure to get an answer to you quicker