diff --git a/tox.ini b/tox.ini
index 095f864..de199fa 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ skipsdist = True
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
+         PYTHONWARNINGS=default::DeprecationWarning
 usedevelop = True
 install_command = pip install -U {opts} {packages}
 deps = -r{toxinidir}/requirements.txt