diff --git a/doc/changes.qbk b/doc/changes.qbk
index 7b467f6c..396eb887 100644
--- a/doc/changes.qbk
+++ b/doc/changes.qbk
@@ -68,5 +68,6 @@ First official release.
   on Visual C++ 2009.
 * Some other minor internal changes to the implementation, tests and
   documentation.
+* Avoid an unnecessary copy in `operator[]`.
 
 [endsect]