diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d8b4f28255..175d1d5ebf 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2356,7 +2356,8 @@ include 'filename'
         is measured in terms of number of write transactions occurring on the
         primary server, it is difficult to predict just how much additional
         grace time will be made available to standby queries.
-        This parameter can only be set at server start.
+        This parameter can only be set in the <filename>postgresql.conf</>
+        file or on the server command line.
        </para>
        <para>
         You should also consider setting <varname>hot_standby_feedback</>
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index b0af9f5c9a..6128694200 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -1881,12 +1881,7 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
-		/*
-		 * Setting this to a higher value without restarting postmaster
-		 * can cause various bugs in TOAST object removal, CLUSTER and
-		 * possibly other places, so this must be changed only on restart.
-		 */
-		{"vacuum_defer_cleanup_age", PGC_POSTMASTER, REPLICATION_MASTER,
+		{"vacuum_defer_cleanup_age", PGC_SIGHUP, REPLICATION_MASTER,
 			gettext_noop("Number of transactions by which VACUUM and HOT cleanup should be deferred, if any."),
 			NULL
 		},