diff --git a/tox.ini b/tox.ini
index 58ee004c..00ad22b8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -48,4 +48,5 @@ commands = coverage erase
 description = invoke sphinx-build to build the HTML docs
 basepython = python3.7
 deps = sphinx >= 1.7.5, < 2
+       jinja2 < 3.1.0
 commands = make -C docs/ html
\ No newline at end of file