diff --git a/ChangeLog b/ChangeLog
index 00c9d98b11..d357bb6f6e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -72,6 +72,11 @@ Sat Dec  6 14:35:06 2008  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* pack.c (pack_unpack): ditto.
 
+Fri Dec  5 22:56:24 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* eval.c (rb_make_exception): single argument to raise may be
+	  string compatible object.
+
 Fri Dec  5 21:45:45 2008  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* rational.c (nurat_{to_s,inspect}): performance improvement.
diff --git a/eval.c b/eval.c
index 636c225565..9c99711ce9 100644
--- a/eval.c
+++ b/eval.c
@@ -477,13 +477,13 @@ rb_make_exception(int argc, VALUE *argv)
     mesg = Qnil;
     switch (argc) {
       case 0:
-	mesg = Qnil;
 	break;
       case 1:
 	if (NIL_P(argv[0]))
 	    break;
-	if (TYPE(argv[0]) == T_STRING) {
-	    mesg = rb_exc_new3(rb_eRuntimeError, argv[0]);
+	mesg = rb_check_string_type(argv[0]);
+	if (!NIL_P(mesg)) {
+	    mesg = rb_exc_new3(rb_eRuntimeError, mesg);
 	    break;
 	}
 	n = 0;