diff --git a/tox.ini b/tox.ini
index dd5b2dac0694..17172ad43567 100644
--- a/tox.ini
+++ b/tox.ini
@@ -127,7 +127,7 @@ commands = {[testenv:docs]commands}
 commands = bandit -c bandit.yaml -r nova -n 5 -ll
 
 [testenv:releasenotes]
-commands = sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
+commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [flake8]
 # E125 is deliberately excluded. See https://github.com/jcrocholl/pep8/issues/126