diff --git a/ChangeLog b/ChangeLog
index c79aa7600c..1cac23e0d5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Dec 12 17:11:57 2015  CHIKANAGA Tomoyuki  <nagachika@ruby-lang.org>
+
+	* doc/NEWS-0.2.2: add description about incompatible change in Hash
+	  duplicated key overriding policy. [Bug #10315] [Bug #11501]
+
 Sat Dec 12 07:44:38 2015  Eric Wong  <e@80x24.org>
 
 	* io.c (do_io_advise): do not raise on ENOSYS
diff --git a/doc/NEWS-2.2.0 b/doc/NEWS-2.2.0
index b4ef080249..70ccddf32d 100644
--- a/doc/NEWS-2.2.0
+++ b/doc/NEWS-2.2.0
@@ -105,6 +105,11 @@ with all sufficient information, see the ChangeLog file.
     * Rename GC.stat entries. [Feature #9924]
       See https://docs.google.com/spreadsheets/d/11Ua4uBr6o0k-nORrZLEIIUkHJ9JRzRR0NyZfrhEEnc8/edit?usp=sharing
 
+* Hash
+  * incompatible changes:
+    * Change overriding policy for duplicated key. [Bug #10315]
+      { **hash1, **hash2 } contains values of hash2 for duplicated keys.
+
 * IO
   * incompatible changes:
     * When flushing file IO with IO#flush, you cannot assume that the metadata