diff --git a/tox.ini b/tox.ini
index 54fdd6a..1333b9e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,7 @@ usedevelop = True
 install_command = pip install -U {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
+   PYTHONWARNINGS=default::DeprecationWarning
 deps = -r{toxinidir}/test-requirements.txt
 commands = python setup.py test --slowest --testr-args='{posargs}'