diff --git a/ChangeLog b/ChangeLog
index 30f2772f23..a71be800d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,6 @@
 Wed Jan 20 17:13:39 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
-
+	* tool/extlibs.rb: add --cache option to change cache directory.
 
 Tue Jan 19 17:03:40 2016  Martin Duerst  <duerst@it.aoyama.ac.jp>