diff --git a/setup.py b/setup.py
index c48b7119..1810243c 100644
--- a/setup.py
+++ b/setup.py
@@ -108,7 +108,7 @@ extras_require_all = extras_require_twisted + extras_require_asyncio + \
 
 # development dependencies
 #
-extras_require_dev = ["pep8", "flake8", "mock>=1.0.1", "pytest>=2.6.4"]
+extras_require_dev = ["pep8", "flake8", "mock>=1.0.1", "pytest>=2.6.4", "unittest2>=1.1.0"]
 
 # for testing by users with "python setup.py test" (not Tox, which we use)
 #