--- a/test/base.py
+++ b/test/base.py
@@ -23,9 +23,9 @@
 import re
 import pkg_resources
 import json
-from mock import patch, MagicMock
+from unittest.mock import patch, MagicMock
 from copy import deepcopy
-from six import StringIO
+from io import StringIO
 
 import mbed_lstools.main as cli
 
--- a/test/mbedls_toolsbase.py
+++ b/test/mbedls_toolsbase.py
@@ -23,7 +23,7 @@
 import re
 import json
 from io import StringIO
-from mock import patch, mock_open, DEFAULT
+from unittest.mock import patch, mock_open, DEFAULT
 from copy import deepcopy
 
 from mbed_lstools.lstools_base import MbedLsToolsBase, FSInteraction
--- a/test/os_linux_generic.py
+++ b/test/os_linux_generic.py
@@ -19,7 +19,7 @@
 import unittest
 import sys
 import os
-from mock import patch, mock_open
+from unittest.mock import patch, mock_open
 from mbed_lstools.linux import MbedLsToolsLinuxGeneric
 
 
--- a/test/platform_database.py
+++ b/test/platform_database.py
@@ -22,7 +22,7 @@
 import logging
 import tempfile
 import json
-from mock import patch, MagicMock, DEFAULT
+from unittest.mock import patch, MagicMock, DEFAULT
 from io import StringIO
 
 from mbed_lstools.platform_database import PlatformDatabase, DEFAULT_PLATFORM_DB,\
--- a/test/platform_detection.py
+++ b/test/platform_detection.py
@@ -19,7 +19,7 @@
 import unittest
 import os
 import copy
-from mock import patch, mock_open, DEFAULT
+from unittest.mock import patch, mock_open, DEFAULT
 
 from mbed_lstools.lstools_base import MbedLsToolsBase