diff --git a/lower-constraints.txt b/lower-constraints.txt
index 10d033e..d120b45 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -17,7 +17,6 @@ keystoneauth1==3.4.0
 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/pycadf/tests/test_cadf_spec.py b/pycadf/tests/test_cadf_spec.py
index 416638f..e448218 100644
--- a/pycadf/tests/test_cadf_spec.py
+++ b/pycadf/tests/test_cadf_spec.py
@@ -13,10 +13,9 @@
 # the License.
 
 import time
+from unittest import mock
 import uuid
 
-import mock
-
 from pycadf import attachment
 from pycadf import cadftype
 from pycadf import credential
diff --git a/test-requirements.txt b/test-requirements.txt
index bf35289..c1d3c32 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -8,7 +8,6 @@ flake8-docstrings==0.2.1.post1 # MIT
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 python-subunit>=1.0.0 # Apache-2.0/BSD
-mock>=2.0.0 # BSD
 stestr>=2.0.0 # Apache-2.0
 testtools>=2.2.0 # MIT