diff --git a/lib/auto_update_util.py b/lib/auto_update_util.py
index 35acca9..f77db0a 100644
--- a/lib/auto_update_util.py
+++ b/lib/auto_update_util.py
@@ -8,10 +8,14 @@
 from __future__ import print_function
 
 import re
+import sys
 
 from chromite.lib import cros_logging as logging
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 def GetChromeosBuildInfo(lsb_release_content=None, regex=None):
   """Get chromeos build info in device under test as string. None on fail.
 
diff --git a/lib/auto_update_util_unittest b/lib/auto_update_util_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/auto_update_util_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/auto_update_util_unittest.py b/lib/auto_update_util_unittest.py
index faaf5c3..41105bf 100644
--- a/lib/auto_update_util_unittest.py
+++ b/lib/auto_update_util_unittest.py
@@ -7,10 +7,15 @@
 
 from __future__ import print_function
 
+import sys
+
 from chromite.lib import auto_update_util
 from chromite.lib import cros_test_lib
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class VersionMatchUnittest(cros_test_lib.TestCase):
   """Test version_match function."""
 
diff --git a/lib/auto_updater.py b/lib/auto_updater.py
index 0571294..856c2ac 100644
--- a/lib/auto_updater.py
+++ b/lib/auto_updater.py
@@ -34,6 +34,7 @@
 import os
 import re
 import subprocess
+import sys
 import tempfile
 import time
 
@@ -53,6 +54,10 @@
 
 from chromite.utils import key_value_store
 
+
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 # Naming conventions for global variables:
 #   File on remote host without slash: REMOTE_XXX_FILENAME
 #   File on remote host with slash: REMOTE_XXX_FILE_PATH
diff --git a/lib/auto_updater_transfer.py b/lib/auto_updater_transfer.py
index a59eeff..11aa2f2 100644
--- a/lib/auto_updater_transfer.py
+++ b/lib/auto_updater_transfer.py
@@ -40,6 +40,7 @@
 
 import abc
 import os
+import sys
 
 import six
 from six.moves import urllib
@@ -50,6 +51,10 @@
 from chromite.lib import osutils
 from chromite.lib import retry_util
 
+
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 # Naming conventions for global variables:
 #   Path on remote host with slash: REMOTE_XXX_PATH
 #   File on local server without slash: LOCAL_XXX_FILENAME
diff --git a/lib/auto_updater_transfer_unittest b/lib/auto_updater_transfer_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/auto_updater_transfer_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/auto_updater_transfer_unittest.py b/lib/auto_updater_transfer_unittest.py
index 13c45b9..243469c 100644
--- a/lib/auto_updater_transfer_unittest.py
+++ b/lib/auto_updater_transfer_unittest.py
@@ -16,6 +16,7 @@
 
 import copy
 import os
+import sys
 
 import mock
 
@@ -26,6 +27,9 @@
 from chromite.lib import remote_access
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 _DEFAULT_ARGS = {
     'payload_dir': None, 'device_payload_dir': None, 'tempdir': None,
     'payload_name': None, 'cmd_kwargs': None,
diff --git a/lib/auto_updater_unittest b/lib/auto_updater_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/auto_updater_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/auto_updater_unittest.py b/lib/auto_updater_unittest.py
index be9fe64..12bbedb 100644
--- a/lib/auto_updater_unittest.py
+++ b/lib/auto_updater_unittest.py
@@ -17,6 +17,7 @@
 
 import json
 import os
+import sys
 
 import mock
 
@@ -31,6 +32,9 @@
 from chromite.lib import stateful_updater
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class ChromiumOSBaseUpdaterMock(partial_mock.PartialCmdMock):
   """Mock out all update and verify functions in ChromiumOSUpdater."""
   TARGET = 'chromite.lib.auto_updater.ChromiumOSUpdater'
diff --git a/lib/stateful_updater.py b/lib/stateful_updater.py
index 732ae0e..4b43d2a 100644
--- a/lib/stateful_updater.py
+++ b/lib/stateful_updater.py
@@ -15,6 +15,7 @@
 from __future__ import print_function
 
 import os
+import sys
 import tempfile
 
 from chromite.lib import constants
@@ -23,6 +24,9 @@
 from chromite.lib import osutils
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class Error(Exception):
   """Base exception class of StatefulUpdater errors."""
 
diff --git a/lib/stateful_updater_unittest b/lib/stateful_updater_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/stateful_updater_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/stateful_updater_unittest.py b/lib/stateful_updater_unittest.py
index 1d847ac..2448987 100644
--- a/lib/stateful_updater_unittest.py
+++ b/lib/stateful_updater_unittest.py
@@ -9,6 +9,7 @@
 
 import os
 import shutil
+import sys
 
 import mock
 
@@ -22,6 +23,9 @@
 # pylint: disable=protected-access
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class ChromiumOSDeviceMock(partial_mock.PartialMock):
   """Provides a context where RemoteDevice run commands are run locally."""