diff --git a/patroni/api.py b/patroni/api.py
index b09d4185..eb410c91 100644
--- a/patroni/api.py
+++ b/patroni/api.py
@@ -381,7 +381,8 @@ class RestApiHandler(BaseHTTPRequestHandler):
                                        pg_xlog_location_diff(pg_last_xlog_replay_location(), '0/0')::bigint,
                                        to_char(pg_last_xact_replay_timestamp(), 'YYYY-MM-DD HH24:MI:SS.MS TZ'),
                                        pg_is_in_recovery() AND pg_is_xlog_replay_paused(),
-                                       (SELECT json_agg(row_to_json(ri)) FROM replication_info ri)""", retry=retry)[0]
+                                       (SELECT array_to_json(array_agg(row_to_json(ri))) FROM replication_info ri)""",
+                             retry=retry)[0]
 
             result = {
                 'state': self.server.patroni.postgresql.state,
diff --git a/patroni/postgresql.py b/patroni/postgresql.py
index 7264d371..852faa8b 100644
--- a/patroni/postgresql.py
+++ b/patroni/postgresql.py
@@ -80,6 +80,9 @@ class Postgresql(object):
         self._database = config.get('database', 'postgres')
         self._data_dir = config['data_dir']
         self._pending_restart = False
+
+        self._version_file = os.path.join(self._data_dir, 'PG_VERSION')
+        self._major_version = self.get_major_version()
         self._server_parameters = self.get_server_parameters(config)
 
         self._connect_address = config.get('connect_address')
@@ -89,8 +92,6 @@ class Postgresql(object):
 
         self._need_rewind = False
         self._use_slots = config.get('use_slots', True)
-        self._version_file = os.path.join(self._data_dir, 'PG_VERSION')
-        self._major_version = self.get_major_version()
         self._schedule_load_slots = self.use_slots
 
         self._pgpass = config.get('pgpass') or os.path.join(os.path.expanduser('~'), 'pgpass')
@@ -154,7 +155,8 @@ class Postgresql(object):
         parameters = config['parameters'].copy()
         listen_addresses, port = (config['listen'] + ':5432').split(':')[:2]
         parameters.update({'cluster_name': self.scope, 'listen_addresses': listen_addresses, 'port': port})
-        return parameters
+        return {k: v for k, v in parameters.items() if not self._major_version or
+                self._major_version >= self.CMDLINE_OPTIONS.get(k, (0, 1, 9.1))[2]}
 
     def resolve_connection_addresses(self):
         self._local_address = self.get_local_address()
@@ -647,8 +649,7 @@ class Postgresql(object):
             f.write('# Do not edit this file manually!\n# It will be overwritten by Patroni!\n')
             f.write("include '{0}'\n\n".format(self.config.get('custom_conf') or self._postgresql_base_conf_name))
             for name, value in sorted(self._server_parameters.items()):
-                if name not in self.CMDLINE_OPTIONS:
-                    f.write("{0} = '{1}'\n".format(name, value))
+                f.write("{0} = '{1}'\n".format(name, value))
 
     def is_healthy(self):
         if not self.is_running():