diff --git a/.readthedocs.yml b/.readthedocs.yml
index da2ebd5b4..fffae0076 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -18,6 +18,7 @@ build:
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:
    configuration: docs/src/conf.py
+   fail_on_warning: true
 
 # Optionally build your docs in additional formats such as PDF and ePub
 # formats:
diff --git a/tox.ini b/tox.ini
index 56b0a523d..b36676160 100644
--- a/tox.ini
+++ b/tox.ini
@@ -71,7 +71,7 @@ deps =
 
 commands =
     python -m pip install .
-    sphinx-build {posargs:-E} -b html docs/src docs/build/html
+    sphinx-build {posargs:-E} -W -b html docs/src docs/build/html
 
 [flake8]
 # longer lines for compatibility with other linters