diff --git a/ChangeLog b/ChangeLog
index 936407865b..ac54ab9c78 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Oct 18 12:58:15 2015  Tanaka Akira  <akr@fsij.org>
+
+	* lib/securerandom.rb: Specify frozen_string_literal: true.
+
 Sun Oct 18 11:22:52 2015  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* dln.c: remove defined(__WATCOMC__).
diff --git a/lib/securerandom.rb b/lib/securerandom.rb
index 2f34e78374..49995d9eb3 100644
--- a/lib/securerandom.rb
+++ b/lib/securerandom.rb
@@ -1,4 +1,5 @@
 # -*- coding: us-ascii -*-
+# -*- frozen_string_literal: true -*-
 begin
   require 'openssl'
 rescue LoadError