diff --git a/docs/requirements.txt b/docs/requirements.txt
index 417ec352..f6f83f25 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -7,7 +7,7 @@ imagesize==0.7.1
 javalang==0.10.1
 javasphinx==0.9.14
 Jinja2==2.8
-lxml==3.6.4
+lxml==4.6.3
 MarkupSafe==0.23
 Pygments==2.1.3
 pytz==2016.7