--- a/docs/conf.py
+++ b/docs/conf.py
@@ -16,7 +16,7 @@
 
 # HACKS: pytables is a difficult dependency to build, so just mock it when
 # generating docs - this makes sure the docs build fully for ulmo.readthedocs.org
-import mock
+from unittest import mock
 sys.modules['tables'] = mock.MagicMock()
 sys.modules['tables.scripts'] = mock.MagicMock()
 
--- a/test/test_util.py
+++ b/test/test_util.py
@@ -7,7 +7,7 @@
 import tempfile
 
 import httpretty as httpretty
-import mock
+from unittest import mock
 
 
 def get_test_file_path(file_path):