diff --git a/ChangeLog b/ChangeLog
index 25e54ec583..285065f9f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jul 31 14:38:10 2013  Akinori MUSHA  <knu@iDaemons.org>
+
+	* lib/set.rb: [DOC] Use the term "sorted" instead "ordered" when
+	  mentioning SortSet.
+
 Wed Jul 31 12:18:47 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (big2str_struct): New structure.
diff --git a/lib/set.rb b/lib/set.rb
index aec22ef4fe..2e28b027ba 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -15,7 +15,7 @@
 # This library provides the Set class, which deals with a collection
 # of unordered values with no duplicates.  It is a hybrid of Array's
 # intuitive inter-operation facilities and Hash's fast lookup.  If you
-# need to keep values ordered, use the SortedSet class.
+# need to keep values sorted in some order, use the SortedSet class.
 #
 # The method +to_set+ is added to Enumerable for convenience.
 #