diff --git a/ChangeLog b/ChangeLog
index 595f2cf058..c1e51c1b11 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Dec 17 23:44:15 2013  Kazuki Tsujimoto  <kazuki@callcc.net>
+
+	* test/ruby/test_io.rb: fix duplicated test name.
+
 Tue Dec 17 20:15:00 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* hash.c (rb_hash_reject): revert to deprecated behavior, with
diff --git a/test/ruby/test_io.rb b/test/ruby/test_io.rb
index 8eb94e367a..6af318c706 100644
--- a/test/ruby/test_io.rb
+++ b/test/ruby/test_io.rb
@@ -2969,7 +2969,7 @@ End
     t.kill
   end
 
-  def test_s_write
+  def test_io_s_write
     t = Tempfile.new("test_io")
     t.close
     path = t.path