diff --git a/tools/releasetools/test_utils.py b/tools/releasetools/test_utils.py
index a15ff5b..b9c8dc7 100644
--- a/tools/releasetools/test_utils.py
+++ b/tools/releasetools/test_utils.py
@@ -21,6 +21,7 @@
 import os
 import os.path
 import struct
+import unittest
 
 import common
 
@@ -110,3 +111,10 @@
         fp.write(os.urandom(data_size))
 
   return sparse_image
+
+
+class ReleaseToolsTestCase(unittest.TestCase):
+  """A common base class for all the releasetools unittests."""
+
+  def tearDown(self):
+    common.Cleanup()