diff --git a/ChangeLog b/ChangeLog
index eaf54a7746..2a1b9d8cce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Dec 22 22:09:01 2015  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* NEWS: Added news entry of RDoc 4.2.1
+
 Tue Dec 22 21:20:00 2015  Kenta Murata  <mrkn@mrkn.jp>
 
 	* ext/bigdecimal/bigdecimal.gemspec: bump version to 1.2.8.
diff --git a/NEWS b/NEWS
index c4f444a822..9cca7d92b0 100644
--- a/NEWS
+++ b/NEWS
@@ -286,6 +286,11 @@ with all sufficient information, see the ChangeLog file.
 * Rake
   * Rake is removed from stdlib.  [Feature #11025]
 
+* RDoc
+  * Updated to RDoc 4.2.1.  For full release notes see:
+
+    https://github.com/rdoc/rdoc/blob/master/History.rdoc#421--2015-12-22
+
 * RubyGems
   * Updated to RubyGems 2.5.1.  For full release notes see: