diff --git a/tox.ini b/tox.ini
index 01609f092..dbfa51cc0 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 =
   {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}