diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index 86239922cc0..7d656af1da7 100644
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -569,7 +569,8 @@ rsync --archive --delete --hard-links --size-only --no-inc-recursive /vol1/pg_tb
        Configure the servers for log shipping.  (You do not need to run
        <function>pg_start_backup()</function> and <function>pg_stop_backup()</function>
        or take a file system backup as the standbys are still synchronized
-       with the primary.)
+       with the primary.)  Replication slots are not copied and must
+       be recreated.
       </para>
      </step>