The following crashes for me with CFFI (master) and sbcl-1.0.58 (actually as early as sbcl-1.0.57-49-gd720bc3) on amd64/x86_64: https://gist.github.com/fa8f380a218b55b4ae6a (This is a simplified case of a callback being used in cl-cairo2.) Altering some things causes it not to crash: * Not declaring P with DYNAMIC-EXTENT. * Not using STATUS_T as a return type, simply using :INT and 0. * Altering the FORMAT to a simpler version. However, I don't think any of these things are in error, and my guess is there is some corruption that happens regardless. This works without error on earlier versions of SBCL as well as CCL, but it's unclear whether something bad is happening silently. Am I doing something wrong here, or is there a bug in CFFI or SBCL? thanks, -- Ryan Pavlik <rpavlik@gmail.com> | https://github.com/rpav 425.220.9585