Index: MultiSource/Applications/siod/slib.c
===================================================================
--- MultiSource/Applications/siod/slib.c
+++ MultiSource/Applications/siod/slib.c
@@ -129,7 +129,7 @@
 struct user_type_hooks *user_types = NULL;
 long user_tc_next = tc_user_min;
 struct gc_protected *protected_registers = NULL;
-jmp_buf save_regs_gc_mark;
+ucontext_t ucontext;
 double gc_rt;
 long gc_cells_collected;
 char *user_ch_readm = "";
@@ -1266,9 +1266,9 @@
    {heap->type = tc_free_cell;
     heap->gc_mark = 0;
     ++heap;}
- setjmp(save_regs_gc_mark);
- mark_locations((LISP *) save_regs_gc_mark,
-		(LISP *) (((char *) save_regs_gc_mark) + sizeof(save_regs_gc_mark)));
+ getcontext(&ucontext);
+ mark_locations((LISP *) &ucontext.uc_mcontext,
+                (LISP *) (((char *) &ucontext.uc_mcontext) + sizeof(mcontext_t)));
  mark_protected_registers();
  mark_locations((LISP *) stack_start_ptr,
 		(LISP *) &stack_end);