diff --git a/requirements.txt b/requirements.txt
index c0b6a49..1193b39 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,3 +2,4 @@
 sphinx<2
 sphinx-rtd-theme<0.5
 readthedocs-sphinx-ext<2.3
+jinja2<3.1.0