diff --git a/docs/requirements.txt b/docs/requirements.txt
index dc9493b..f593cb9 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -60,7 +60,7 @@ itsdangerous==1.1.0
 Jinja2==2.11.2
 joblib==0.15.1
 kiwisolver==1.2.0
-lxml==4.5.0
+lxml==4.9.1
 MarkupSafe==1.1.1
 matplotlib==3.2.1
 mendeleev==0.6.0