diff --git a/c/scheme48vm.h b/c/scheme48vm.h
index 70ea4cf..a045f19 100644
--- a/c/scheme48vm.h
+++ b/c/scheme48vm.h
@@ -56,6 +56,6 @@ extern s48_value	s48_add_channel(s48_value, s48_value, long);
 extern s48_value	s48_allocate_stob(long type, long size);
 extern void		s48_push_gc_rootsB(char *, long);
 extern char		s48_pop_gc_rootsB(void);
-extern char *		s48_set_gc_roots_baseB(void);
-extern char		s48_release_gc_roots_baseB(char *);
+extern char *		s48_set_gc_roots_baseB(char **);
+extern char		s48_release_gc_roots_baseB(char *, char*);
 extern void		s48_register_gc_rootB(char *marker);