diff --git a/tox.ini b/tox.ini
index cc68410c..bad15eee 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ envlist = py35,py34,py27,pep8
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
+         PYTHONWARNINGS=default::DeprecationWarning
 usedevelop = True
 install_command = pip install {opts} {packages}