diff --git a/tox.ini b/tox.ini
index 7f52c2f..f642b92 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,5 +3,6 @@ envlist = py27,py34
 [testenv]
 deps=
 	pytest
+	mock
 	git+http://people.csail.mit.edu/hubert/git/pyaudio.git
 commands=py.test tests/