diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index f3eb7fbd338..d0652276564 100644
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -619,7 +619,8 @@ 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_backup_start()</function> and <function>pg_backup_stop()</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>