diff --git a/requirements.txt b/requirements.txt
index ed7ecf5..c890ed3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -24,7 +24,7 @@ jupyter-client==5.2.3
 jupyter-core==4.4.0
 lipsum==0.1.2
 Logbook==1.4.0
-lxml==4.2.4
+lxml==4.9.1
 Mako==1.0.7
 Markdown==2.6.11
 MarkupSafe==1.0