diff --git a/tox.ini b/tox.ini
index ffe3494..61a7e3c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -43,6 +43,7 @@ commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]