The following code is nonsense but a segfalut should never happen: guile> (define t (procedure->syntax (display 'b))) Program received signal SIGSEGV, Segmentation fault. 0x40021532 in scm_m_define (x=1075300008, env=1075300056) at eval.c:881 881 if (SCM_CLOSUREP (arg1) Could someone please verify this? Jost