diff --git a/tox.ini b/tox.ini
index 6854896..a6a8269 100644
--- a/tox.ini
+++ b/tox.ini
@@ -42,6 +42,7 @@ basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:debug]
+basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:releasenotes]