diff --git a/tests/testcase_with_tmpdir.py b/tests/testcase_with_tmpdir.py
index 2e05eeb..a6bcf1e 100644
--- a/tests/testcase_with_tmpdir.py
+++ b/tests/testcase_with_tmpdir.py
@@ -1,4 +1,5 @@
 """Extension of unittest.TestCase to create a temp directory tmpdir."""
+import sys
 import os.path
 import unittest
 import tempfile