Hello SLIME developers, Please consider swapping COND clauses for :win32 and :sb-thread for SBCL backend's PREFERRED-COMMUNICATION-STYLE, in order to select :spawn communication style if :sb-thread is available. Like this: (defimplementation preferred-communication-style () (cond ((member :sb-thread *features*) :spawn) ;; fixme: when SBCL/win32 gains better select() support, remove ;; this. ((member :win32 *features*) nil) (t :fd-handler))) For now, it makes no difference for mainline SBCL users, but this change will be required when the thread support for Windows will be merged, anyway. (And, as you can see, the fact that no one but me is responsible for unofficial Windows fork's behavior won't protect you from questions and (maybe) bug reports for problems with SLIME + unofficial SBCL). What we have now is the code with a /meaning/ like "even if these guys will add threading to the windows port, it will surely be broken, so let's avoid using it". If the order of clauses were intentional, it would be a funny example of rude and offensive Common Lisp. -- Regards, Anton Kovalenko +7(916)345-34-02 | Elektrostal' MO, Russia