diff --git a/doc/system/changes.adoc b/doc/system/changes.adoc
index 41d71b5..ef8eeac 100644
--- a/doc/system/changes.adoc
+++ b/doc/system/changes.adoc
@@ -1,5 +1,5 @@
 ////
-Copyright 2018-2022 Peter Dimov
+Copyright 2018-2025 Peter Dimov
 Distributed under the Boost Software License, Version 1.0.
 https://www.boost.org/LICENSE_1_0.txt
 ////
@@ -8,6 +8,10 @@ https://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix:
 
+## Changes in Boost 1.91
+
+* The return type of `operator|(result<T&>, U)` has been changed to non-reference.
+
 ## Changes in Boost 1.89
 
 * The stub compiled library has been removed; System has been header-only since release 1.69.