diff --git a/error.c b/error.c
index 075cb1dfb1..18168eda7a 100644
--- a/error.c
+++ b/error.c
@@ -950,6 +950,9 @@ exc_to_s(VALUE exc)
     return rb_String(mesg);
 }
 
+/* FIXME: Include eval_error.c */
+void rb_ec_error_write(VALUE errinfo, VALUE errat, VALUE str);
+
 /*
  * call-seq:
  *   exception.full_message  ->  string
diff --git a/eval_error.c b/eval_error.c
index f602737dd2..b973fc06d6 100644
--- a/eval_error.c
+++ b/eval_error.c
@@ -188,7 +188,7 @@ print_backtrace(const VALUE eclass, const VALUE errat, const VALUE str, int reve
 }
 
 void
-rb_ec_error_write(volatile VALUE errinfo, volatile VALUE errat, volatile VALUE str)
+rb_ec_error_write(VALUE errinfo, VALUE errat, VALUE str)
 {
     volatile VALUE eclass = Qundef, emesg = Qundef;