Test code to show problem with dynamic memory with deftest of https://github.com/fukamachi/prove To exhaust dynamic memory do either of the three below. (ql:quickload :prove-fail :verbose t) or (asdf:load-system :prove-fail :verbose t) or (ql:quickload :prove) (load "package.lisp") (load "macros.lisp") (compile-file "deftests.lisp" :verbose t)