diff --git a/neutron/tests/fullstack/resources/config.py b/neutron/tests/fullstack/resources/config.py
index 1873b603fd9..6a0dc0c316a 100644
--- a/neutron/tests/fullstack/resources/config.py
+++ b/neutron/tests/fullstack/resources/config.py
@@ -426,6 +426,7 @@ class L3ConfigFixture(ConfigFixture):
         self.config['DEFAULT'].update({
             'debug': 'True',
             'test_namespace_suffix': self._generate_namespace_suffix(),
+            'ha_keepalived_state_change_server_threads': '1',
         })
         self.config.update({
             'agent': {'use_helper_for_ns_read': 'False'}