diff --git a/tox.ini b/tox.ini
index 6f35361..82910c3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,8 @@ commands = {posargs}
 commands = doc8 -v doc README.rst
 
 [testenv:docs]
+setenv =
+  SPHINX_WARNINGS_TRANS=1
 commands = docstheme-build-translated.sh
 
 [doc8]