diff --git a/docs/requirements.txt b/docs/requirements.txt
index 8b08d28..0a044ca 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -2,3 +2,4 @@
 Sphinx~=3.5.3
 m2r2~=0.2.7
 sphinx-rtd-theme~=0.5.1
+mistune~=0.8.4