So, when I send my local changes to cells, I included a change to defmodel that removed :accessor, :reader, and :writer from the generated DEFCLASS, since DEFMODEL turns around and redefines them anyways. Well, it turns out that that tickles a buglet in some versions of SBCL, which causes it to emit scary-sounding warnings. I think it's fixed in 0.8.11, but it might be best to just forget that change.