diff --git a/docs/changes.xml b/docs/changes.xml
index a67a671b..f8198304 100644
--- a/docs/changes.xml
+++ b/docs/changes.xml
@@ -28,6 +28,13 @@ Ruby apps with configured mutlithreading could crash on start under load.
 </para>
 </change>
 
+<change type="bugfix">
+<para>
+Mount points were not unmounted when using "mount" namespace isolation; the
+bug had appeared in 1.21.0.
+</para>
+</change>
+
 </changes>