diff --git a/neutron/tests/fullstack/resources/config.py b/neutron/tests/fullstack/resources/config.py
index 68089c344eb..d839e28f39f 100644
--- a/neutron/tests/fullstack/resources/config.py
+++ b/neutron/tests/fullstack/resources/config.py
@@ -61,7 +61,7 @@ class NeutronConfigFixture(ConfigFixture):
                 'service_plugins': env_desc.service_plugins,
                 'auth_strategy': 'noauth',
                 'debug': 'True',
-                'global_physnet_mtu': env_desc.global_mtu,
+                'global_physnet_mtu': str(env_desc.global_mtu),
                 'agent_down_time': str(env_desc.agent_down_time),
                 'transport_url':
                     'rabbit://%(user)s:%(password)s@%(host)s:5672/%(vhost)s' %