diff --git a/ChangeLog b/ChangeLog
index 698486131e..8ea80685e3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Mar 16 03:40:49 2013  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* test/ruby/test_signal.rb (test_hup_me): added a few comments.
+
 Sat Mar 16 03:39:38 2013  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* thread.c (ruby_kill): added a few comments.
diff --git a/test/ruby/test_signal.rb b/test/ruby/test_signal.rb
index bfc94e8dcb..2cab5eb1db 100644
--- a/test/ruby/test_signal.rb
+++ b/test/ruby/test_signal.rb
@@ -276,6 +276,10 @@ EOS
 
   def test_hup_me
     # [Bug #7951] [ruby-core:52864]
+    # This is MRI specific spec. ruby has no guarantee
+    # that signal will be deliverd synchronously.
+    # This ugly workaround was introduced to don't break
+    # compatibility against silly example codes.
     assert_raise(SignalException) {
       Process.kill('HUP',Process.pid)
     }