diff --git a/doc/src/sgml/ref/pg_basebackup.sgml b/doc/src/sgml/ref/pg_basebackup.sgml
index ac442b81a5..c5cfa87d35 100644
--- a/doc/src/sgml/ref/pg_basebackup.sgml
+++ b/doc/src/sgml/ref/pg_basebackup.sgml
@@ -83,8 +83,14 @@ PostgreSQL documentation
- If you are using -X none, there is no guarantee that all
- WAL files required for the backup are archived at the end of backup.
+ pg_basebackup cannot force the standby
+ to switch to a new WAL file at the end of backup.
+ When you are using -X none, if write activity on
+ the primary is low, pg_basebackup may
+ need to wait a long time for the last WAL file required for the backup
+ to be switched and archived. In this case, it may be useful to run
+ pg_switch_wal on the primary in order to
+ trigger an immediate WAL file switch.