Found this comment in some code I am porting to CFFI: ; Seems like ff-defun-callable should be executed every time. ; In OpenMCL, loading .dfsl file is not enough. ff-defun-callable was my creation when UFFI did not handle callbacks. It was like UFFI in that it Just Wrapped native Lisp implementation FFI callback syntax. Uhhhh... if I am using CFFI, can I just code defcallback at the toplevel and invoke get-callback at runtime when passing the callback to the library? Existing code calls a defun which executes ff-defun-callable each time the app runs. kt