diff --git a/pymongo/mongo_client.py b/pymongo/mongo_client.py
index 90e6a7706f..dd9dd6d33a 100644
--- a/pymongo/mongo_client.py
+++ b/pymongo/mongo_client.py
@@ -1170,8 +1170,8 @@ def _socket_for_reads(self, read_preference, session):
         # for topology type Single."
         # Thread safe: if the type is single it cannot change.
         topology = self._get_topology()
-        single = topology.description.topology_type == TOPOLOGY_TYPE.Single
         server = self._select_server(read_preference, session)
+        single = topology.description.topology_type == TOPOLOGY_TYPE.Single
 
         with self._get_socket(server, session) as sock_info:
             secondary_ok = (single and not sock_info.is_mongos) or (
diff --git a/test/mockupdb/test_op_msg_read_preference.py b/test/mockupdb/test_op_msg_read_preference.py
index ba359a5e05..6ecc229ea1 100644
--- a/test/mockupdb/test_op_msg_read_preference.py
+++ b/test/mockupdb/test_op_msg_read_preference.py
@@ -158,15 +158,12 @@ def test(self):
         else:
             self.fail('unrecognized op_type %r' % operation.op_type)
         # For single mongod we send primaryPreferred instead of primary.
-        if (expected_pref == ReadPreference.PRIMARY and self.single_mongod
-                and operation.name != "command"):
+        if expected_pref == ReadPreference.PRIMARY and self.single_mongod:
             expected_pref = ReadPreference.PRIMARY_PREFERRED
-        with going(operation.function, client) as future:
+        with going(operation.function, client):
             request = expected_server.receive()
             request.reply(operation.reply)
 
-        future()  # No error.
-
         self.assertEqual(expected_pref.document,
                          request.doc.get('$readPreference'))
         self.assertNotIn('$query', request.doc)