diff --git a/neutron/tests/unit/agent/linux/openvswitch_firewall/test_iptables.py b/neutron/tests/unit/agent/linux/openvswitch_firewall/test_iptables.py
index b1af575ddd7..3a72495b296 100644
--- a/neutron/tests/unit/agent/linux/openvswitch_firewall/test_iptables.py
+++ b/neutron/tests/unit/agent/linux/openvswitch_firewall/test_iptables.py
@@ -73,14 +73,18 @@ class TestHelper(base.BaseTestCase):
         self.helper.int_br.get_port_name_list.return_value = [
             'tap1234', 'qvo-1234', 'tap9876', 'qvo-fghfhfh']
         self.helper.int_br.db_get_val.return_value = {'foo': 'bar'}
-        self.helper.load_driver_if_needed()
-        self.assertIsNotNone(self.helper.iptables_driver)
+        with mock.patch.object(iptables_firewall.IptablesFirewallDriver,
+             '_check_netfilter_for_bridges'):
+            self.helper.load_driver_if_needed()
+            self.assertIsNotNone(self.helper.iptables_driver)
 
     def test_get_iptables_driver_instance_has_correct_instance(self):
-        instance = iptables.get_iptables_driver_instance()
-        self.assertIsInstance(
-            instance,
-            iptables_firewall.OVSHybridIptablesFirewallDriver)
+        with mock.patch.object(iptables_firewall.IptablesFirewallDriver,
+             '_check_netfilter_for_bridges'):
+            instance = iptables.get_iptables_driver_instance()
+            self.assertIsInstance(
+                instance,
+                iptables_firewall.OVSHybridIptablesFirewallDriver)
 
     def test_cleanup_port_last_port_marks_cleaned(self):
         self.helper.iptables_driver = mock.Mock()
diff --git a/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py b/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
index 000cac0cfe7..db90390e103 100644
--- a/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
+++ b/neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py
@@ -37,6 +37,7 @@ from neutron.agent.common import ovs_lib
 from neutron.agent.common import polling
 from neutron.agent.common import utils
 from neutron.agent.linux import ip_lib
+from neutron.agent.linux import iptables_firewall
 from neutron.agent.linux import utils as linux_utils
 from neutron.api.rpc.callbacks import resources
 from neutron.objects.ports import Port
@@ -151,7 +152,9 @@ class TestOvsNeutronAgent(object):
                                   'setup_ancillary_bridges',
                                   return_value=[]),\
                 mock.patch('neutron.agent.linux.ip_lib.get_device_mac',
-                           return_value='00:00:00:00:00:01'),\
+                           return_value='00:00:00:00:00:01'), \
+                mock.patch.object(iptables_firewall.IptablesFirewallDriver,
+                                  '_check_netfilter_for_bridges'), \
                 mock.patch(
                     'neutron.agent.common.ovs_lib.BaseOVS.get_bridges'),\
                 mock.patch('oslo_service.loopingcall.FixedIntervalLoopingCall',
diff --git a/tox.ini b/tox.ini
index 0b93928732d..1ceb5552f81 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@ setenv = VIRTUAL_ENV={envdir}
          OS_LOG_CAPTURE={env:OS_LOG_CAPTURE:true}
          OS_STDOUT_CAPTURE={env:OS_STDOUT_CAPTURE:true}
          OS_STDERR_CAPTURE={env:OS_STDERR_CAPTURE:true}
+         OS_TEST_TIMEOUT={env:OS_TEST_TIMEOUT:180}
          PYTHONWARNINGS=default::DeprecationWarning,ignore::DeprecationWarning:distutils,ignore::DeprecationWarning:site
 passenv = TRACE_FAILONLY GENERATE_HASHES http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY TOX_ENV_SRC_MODULES
 usedevelop = True