diff --git a/ChangeLog b/ChangeLog
index 4604f17181..87735ed1c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Jan  7 09:31:18 2007  Tadayoshi Funaba  <tadf@dotrb.org>
+
+	* lib/date/format.rb: updated based on date2 4.0.1.
+
 Sat Jan  6 18:46:34 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (rb_io_getline_fast, rb_io_getline): increase lineno
diff --git a/lib/date/format.rb b/lib/date/format.rb
index bf32ce2477..6cada0f69b 100644
--- a/lib/date/format.rb
+++ b/lib/date/format.rb
@@ -1,5 +1,5 @@
-# format.rb: Written by Tadayoshi Funaba 1999-2006
-# $Id: format.rb,v 2.29 2006-12-30 21:43:41+09 tadf Exp $
+# format.rb: Written by Tadayoshi Funaba 1999-2007
+# $Id: format.rb,v 2.30 2007-01-07 09:16:24+09 tadf Exp $
 
 require 'rational'
 
@@ -1054,6 +1054,8 @@ class DateTime < Date
     super() + iso8601_timediv(n)
   end
 
+  def rfc3339(n=0) iso8601(n) end
+
   def jisx0301(n=0)
     super() + iso8601_timediv(n)
   end