diff --git a/aodh/service.py b/aodh/service.py
index 4ef06a794..56c744264 100644
--- a/aodh/service.py
+++ b/aodh/service.py
@@ -91,7 +91,7 @@ CLI_OPTS = [
 ]
 
 
-def prepare_service(argv=None):
+def prepare_service(argv=None, config_files=None):
     conf = cfg.ConfigOpts()
     oslo_i18n.enable_lazy()
     log.register_options(conf)
@@ -106,7 +106,8 @@ def prepare_service(argv=None):
         conf.register_opts(list(options),
                            group=None if group == "DEFAULT" else group)
 
-    conf(argv, project='aodh', validate_default_values=True)
+    conf(argv, project='aodh', validate_default_values=True,
+         default_config_files=config_files)
     log.setup(conf, 'aodh')
     messaging.setup()
     return conf
diff --git a/aodh/tests/functional/api/__init__.py b/aodh/tests/functional/api/__init__.py
index 62980f8ac..eb22801a8 100644
--- a/aodh/tests/functional/api/__init__.py
+++ b/aodh/tests/functional/api/__init__.py
@@ -35,7 +35,7 @@ class FunctionalTest(db_test_base.TestBase):
 
     def setUp(self):
         super(FunctionalTest, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.setup_messaging(self.CONF)
 
diff --git a/aodh/tests/functional/api/test_app.py b/aodh/tests/functional/api/test_app.py
index 740d3811c..da3e28d22 100644
--- a/aodh/tests/functional/api/test_app.py
+++ b/aodh/tests/functional/api/test_app.py
@@ -28,7 +28,7 @@ class TestApp(base.BaseTestCase):
 
     def setUp(self):
         super(TestApp, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
 
     def test_api_paste_file_not_exist(self):
diff --git a/aodh/tests/functional/db.py b/aodh/tests/functional/db.py
index 849abe8b9..5f4df0af6 100644
--- a/aodh/tests/functional/db.py
+++ b/aodh/tests/functional/db.py
@@ -145,7 +145,7 @@ class TestBase(testscenarios.testcase.WithScenarios, test_base.BaseTestCase):
             raise testcase.TestSkipped(
                 'Test is not applicable for %s' % engine)
 
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.CONF.set_override('connection', self.db_url, group="database")
 
diff --git a/aodh/tests/functional/gabbi/fixtures.py b/aodh/tests/functional/gabbi/fixtures.py
index 89f7fcc1b..d4ddb6059 100644
--- a/aodh/tests/functional/gabbi/fixtures.py
+++ b/aodh/tests/functional/gabbi/fixtures.py
@@ -52,7 +52,7 @@ class ConfigFixture(fixture.GabbiFixture):
         if db_url is None:
             raise case.SkipTest('No database connection configured')
 
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         # NOTE(jd): prepare_service() is called twice: first by load_app() for
         # Pecan, then Pecan calls pastedeploy, which starts the app, which has
         # no way to pass the conf object so that Paste apps calls again
diff --git a/aodh/tests/functional/storage/test_get_connection.py b/aodh/tests/functional/storage/test_get_connection.py
index 10ad2f2db..0bab3c565 100644
--- a/aodh/tests/functional/storage/test_get_connection.py
+++ b/aodh/tests/functional/storage/test_get_connection.py
@@ -30,7 +30,7 @@ import six
 class EngineTest(base.BaseTestCase):
     def setUp(self):
         super(EngineTest, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
 
     def test_get_connection(self):
@@ -52,7 +52,7 @@ class EngineTest(base.BaseTestCase):
 class ConnectionRetryTest(base.BaseTestCase):
     def setUp(self):
         super(ConnectionRetryTest, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
 
     def test_retries(self):
@@ -81,7 +81,7 @@ class ConnectionRetryTest(base.BaseTestCase):
 class ConnectionConfigTest(base.BaseTestCase):
     def setUp(self):
         super(ConnectionConfigTest, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
 
     def test_only_default_url(self):
diff --git a/aodh/tests/unit/evaluator/base.py b/aodh/tests/unit/evaluator/base.py
index 8910a7907..46c1311eb 100644
--- a/aodh/tests/unit/evaluator/base.py
+++ b/aodh/tests/unit/evaluator/base.py
@@ -24,7 +24,7 @@ from aodh import service
 class TestEvaluatorBase(base.BaseTestCase):
     def setUp(self):
         super(TestEvaluatorBase, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.conf = self.useFixture(fixture.Config(conf)).conf
         self.api_client = mock.Mock()
         self.useFixture(mockpatch.Patch('ceilometerclient.client.get_client',
diff --git a/aodh/tests/unit/test_coordination.py b/aodh/tests/unit/test_coordination.py
index 4f472dd96..6d2696e59 100644
--- a/aodh/tests/unit/test_coordination.py
+++ b/aodh/tests/unit/test_coordination.py
@@ -109,7 +109,7 @@ class TestPartitioning(base.BaseTestCase):
 
     def setUp(self):
         super(TestPartitioning, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.shared_storage = {}
 
diff --git a/aodh/tests/unit/test_evaluator.py b/aodh/tests/unit/test_evaluator.py
index 8a7fbe318..3a8a3d84c 100644
--- a/aodh/tests/unit/test_evaluator.py
+++ b/aodh/tests/unit/test_evaluator.py
@@ -26,7 +26,7 @@ from aodh.tests import base as tests_base
 class TestAlarmEvaluationService(tests_base.BaseTestCase):
     def setUp(self):
         super(TestAlarmEvaluationService, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.setup_messaging(self.CONF)
 
diff --git a/aodh/tests/unit/test_event.py b/aodh/tests/unit/test_event.py
index fd111925c..4ce2a46ed 100644
--- a/aodh/tests/unit/test_event.py
+++ b/aodh/tests/unit/test_event.py
@@ -28,7 +28,7 @@ class TestEventAlarmEvaluationService(tests_base.BaseTestCase):
     def setUp(self):
         super(TestEventAlarmEvaluationService, self).setUp()
 
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.storage_conn = mock.MagicMock()
         self.setup_messaging(self.CONF)
diff --git a/aodh/tests/unit/test_notifier.py b/aodh/tests/unit/test_notifier.py
index 2f78073e8..6dc972a84 100644
--- a/aodh/tests/unit/test_notifier.py
+++ b/aodh/tests/unit/test_notifier.py
@@ -45,7 +45,7 @@ class TestAlarmNotifier(tests_base.BaseTestCase):
 
     def setUp(self):
         super(TestAlarmNotifier, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.setup_messaging(self.CONF)
         self.service = notifier.AlarmNotifierService(self.CONF)
diff --git a/aodh/tests/unit/test_rpc.py b/aodh/tests/unit/test_rpc.py
index fd7c8004d..627c1d3ca 100644
--- a/aodh/tests/unit/test_rpc.py
+++ b/aodh/tests/unit/test_rpc.py
@@ -47,7 +47,7 @@ class FakeNotifier(object):
 class TestRPCAlarmNotifier(tests_base.BaseTestCase):
     def setUp(self):
         super(TestRPCAlarmNotifier, self).setUp()
-        conf = service.prepare_service([])
+        conf = service.prepare_service(argv=[], config_files=[])
         self.CONF = self.useFixture(fixture_config.Config(conf)).conf
         self.setup_messaging(self.CONF)