diff --git a/neutron_tempest_plugin/api/test_subnets.py b/neutron_tempest_plugin/api/test_subnets.py
index 23574ee..126dc70 100644
--- a/neutron_tempest_plugin/api/test_subnets.py
+++ b/neutron_tempest_plugin/api/test_subnets.py
@@ -24,6 +24,8 @@
 
     @classmethod
     def resource_setup(cls):
+        if 'subnet-external-network' in cls.get_loaded_network_extensions():
+            cls.list_kwargs['router:external'] = False
         super(SubnetsSearchCriteriaTest, cls).resource_setup()
         net = cls.create_network(network_name='subnet-search-test-net')
         for name in cls.resource_names:
@@ -67,8 +69,6 @@
 
     @decorators.idempotent_id('c0f9280b-9d81-4728-a967-6be22659d4c8')
     def test_list_validation_filters(self):
-        if 'subnet-external-network' in self.get_loaded_network_extensions():
-            self.list_kwargs['router:external'] = False
         self._test_list_validation_filters(self.list_kwargs)
         self._test_list_validation_filters({
             'unknown_filter': 'value'}, filter_is_valid=False)