diff --git a/requirements.txt b/requirements.txt
index 339d6be..ba8b3bf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -46,7 +46,7 @@ jupyterlab-server==1.0.6
 kiwisolver==1.1.0
 Logbook==1.5.3
 lru-dict==1.1.6
-lxml==4.4.1
+lxml==4.9.1
 Mako==1.1.0
 MarkupSafe==1.1.1
 matplotlib==3.1.1