diff --git a/api/controller/android_unittest.py b/api/controller/android_unittest.py
index 4e5d65c..2a53c74 100644
--- a/api/controller/android_unittest.py
+++ b/api/controller/android_unittest.py
@@ -7,6 +7,8 @@
 
 from __future__ import print_function
 
+import sys
+
 import mock
 
 from chromite.api import api_config
@@ -21,6 +23,9 @@
 from chromite.service import packages
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class MarkStableTest(cros_test_lib.MockTestCase, api_config.ApiConfigMixin):
   """Unittests for MarkStable."""