diff --git a/pg_upgradecluster b/pg_upgradecluster
index 09979c3..1698ba8 100755
--- a/pg_upgradecluster
+++ b/pg_upgradecluster
@@ -743,7 +743,7 @@ if (not exists $ENV{'PG_CLUSTER_CONF_ROOT'} and -d '/run/systemd/system' and $>
 $start = ($info{running} or $upgrade_scripts) if ($start == -1);
 if ($start) {
     print "Starting upgraded cluster on port $newinfo{port}...\n";
-    @argv = ('pg_ctlcluster', $newversion, $newcluster, 'start');
+    @argv = ('pg_ctlcluster', $newversion, $newcluster, 'start', '--', '-o', "\"-csynchronous_standby_names=''\"");
     error "Could not start upgraded cluster; please check configuration and log files" if system @argv;
 }