diff --git a/tox.ini b/tox.ini
index f3e34d45..e0ed461d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,6 +8,7 @@ skipsdist = True
 # random hash seed successfully.
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
+         PYTHONWARNINGS=default::DeprecationWarning
 usedevelop = True
 install_command = {toxinidir}/tools/tox_install.sh {opts} {packages}
 deps = -r{toxinidir}/requirements.txt