diff --git a/requirements/docs.txt b/requirements/docs.txt
index 7f2655b4c..a61666c3e 100644
--- a/requirements/docs.txt
+++ b/requirements/docs.txt
@@ -1,5 +1,6 @@
 docutils==0.16.0
 m2r==0.2.1
+markdown<3.4.0
 mistune==0.8.4
 myst-parser
 -e git+https://github.com/open-mmlab/pytorch_sphinx_theme.git#egg=pytorch_sphinx_theme