Interaction showing the problem $ guile GNU Guile 2.2.6 Copyright (C) 1995-2019 Free Software Foundation, Inc. Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'. This program is free software, and you are welcome to redistribute it under certain conditions; type `,show c' for details. Enter `,help' for help. scheme@(guile-user)> (use-modules (system vm program)) scheme@(guile-user)> program-arities ERROR: Unbound variable: program-arities. ; should be defined Entering a new prompt. Type `,bt' for a backtrace or `,q' to continue. scheme@(guile-user)> (arity:nreq +) ; 0 arguments required, correct $1 = 0 scheme@(guile-user)> (arity:rest? +) ; rest argument, correct $2 = #f scheme@(guile-user)> (arity:nreq car) ; 1 argument required, bad $3 = 0 scheme@(guile-user)> (program-arguments-alist car) ; correct $4 = ((required _) (optional) (keyword) (allow-other-keys? . #f) (rest . #f)) scheme@(guile-user)> The same thing happens in Guile 3, and on both Mac and Linux.