On Fri, Sep 11, 2009 at 10:49 AM, Volkan YAZICI <yazicivo at ttmail.com> wrote: > (setf (foreign-slot-value data-ptr 'data 'ptr) 0 At first sight, this seems to be the problem because 0 is not a pointer. You want to use (null-pointer) instead. -- Luís Oliveira http://student.dei.uc.pt/~lmoliv/