diff --git a/lower-constraints.txt b/lower-constraints.txt
index cb2ca9db..ea25c29c 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -28,7 +28,7 @@ fixtures==3.0.0
 funcsigs==1.0.0
 futurist==1.2.0
 greenlet==0.4.10
-horizon==17.1.0
+horizon==18.3.0
 idna==2.6
 imagesize==0.7.1
 iso8601==0.1.11
@@ -42,7 +42,6 @@ kombu==4.0.0
 linecache2==1.0.0
 MarkupSafe==1.0
 mccabe==0.2.1
-mock==2.0.0
 monotonic==0.6
 mox3==0.20.0
 msgpack-python==0.4.0
diff --git a/monitoring/alarmdefs/tests.py b/monitoring/alarmdefs/tests.py
index 334f199b..b3756334 100644
--- a/monitoring/alarmdefs/tests.py
+++ b/monitoring/alarmdefs/tests.py
@@ -14,7 +14,7 @@
 # under the License.
 
 from django.urls import reverse
-from mock import patch
+from unittest.mock import patch
 
 from monitoring.alarmdefs import constants
 from monitoring.alarmdefs import views
diff --git a/monitoring/alarms/tests.py b/monitoring/alarms/tests.py
index 39900273..cce6254a 100644
--- a/monitoring/alarms/tests.py
+++ b/monitoring/alarms/tests.py
@@ -11,7 +11,7 @@
 #  under the License.
 
 from django.urls import reverse
-from mock import patch
+from unittest.mock import patch
 
 from monitoring.alarms import constants
 from monitoring.alarms import tables
diff --git a/monitoring/notifications/tests.py b/monitoring/notifications/tests.py
index 01076bae..10c1051c 100644
--- a/monitoring/notifications/tests.py
+++ b/monitoring/notifications/tests.py
@@ -11,7 +11,7 @@
 #  under the License.
 
 from django.urls import reverse
-from mock import patch
+from unittest.mock import patch
 
 from monitoring.notifications import constants
 from monitoring.test import helpers
diff --git a/monitoring/test/helpers.py b/monitoring/test/helpers.py
index d385487b..1f05bd29 100644
--- a/monitoring/test/helpers.py
+++ b/monitoring/test/helpers.py
@@ -16,8 +16,8 @@ import unittest
 import warnings
 
 from django.core.handlers import wsgi
-import mock
 from openstack_dashboard.test import helpers
+from unittest import mock
 
 from monitoring.test.test_data import utils as test_data_utils
 
diff --git a/monitoring/test/test_alarm_tables.py b/monitoring/test/test_alarm_tables.py
index e549ae62..c89f8654 100644
--- a/monitoring/test/test_alarm_tables.py
+++ b/monitoring/test/test_alarm_tables.py
@@ -14,7 +14,7 @@
 
 from django.test import TestCase
 from django.test.utils import override_settings
-from mock import Mock
+from unittest.mock import Mock
 
 import monitoring.alarms.tables
 
diff --git a/monitoring/test/test_client.py b/monitoring/test/test_client.py
index 1ccd24c0..267a1ff2 100644
--- a/monitoring/test/test_client.py
+++ b/monitoring/test/test_client.py
@@ -16,8 +16,8 @@
 
 from django.conf import settings as d_settings
 from django.test.utils import override_settings
-from mock import Mock
-from mock import patch
+from unittest.mock import Mock
+from unittest.mock import patch
 
 from monascaclient import client as mon_client
 from monascaclient import v2_0
diff --git a/test-requirements.txt b/test-requirements.txt
index dc96086c..54f4306d 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -5,7 +5,6 @@
 hacking>=3.0.1,<3.1.0 # Apache-2.0
 
 coverage!=4.4,>=4.0 # Apache-2.0
-mock>=2.0.0 # BSD
 nodeenv>=0.9.4 # BSD
 selenium>=2.50.1 # Apache-2.0