diff --git a/requirements.txt b/requirements.txt
index f134a71..012c93d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,7 +15,7 @@ itsdangerous==0.24
 jedi==0.10.2
 Jinja2==2.9.6
 jsonschema==2.6.0
-lxml==3.8.0
+lxml==4.9.1
 Markdown==2.2.0
 MarkupSafe==1.0
 matplotlib==2.0.2