In swank-openmcl.lisp, there's a function called CLOSURE-CLOSED-OVER- VALUES. For about a year now, OpenMCL has included CCL::CLOSURE-CLOSED-OVER- VALUES, which produces results in the expected format, and should probably be used instead. It correctly displays the closed-over values on x86-64 OpenMCL---the function in swank-openmcl.lisp doesn't. Alternatively, (ccl::%svref closure (+ 1 (- howmany n))) could be replaced with (ccl::nth-immediate closure (+ 1 (- howmany n))) NTH-IMMEDIATE has been around for over 2 years, and I would hope that nobody is running an OpenMCL older than that...