diff --git a/buildbot/cbuildbot_stages_unittest.py b/buildbot/cbuildbot_stages_unittest.py
index d70f04cb..9da9e1c 100755
--- a/buildbot/cbuildbot_stages_unittest.py
+++ b/buildbot/cbuildbot_stages_unittest.py
@@ -19,6 +19,7 @@
 import sys
 import tempfile
 import time
+import unittest
 
 import constants
 sys.path.insert(0, constants.SOURCE_ROOT)