diff --git a/requirements.txt b/requirements.txt
index 1e06e0b8..40c5459a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -19,7 +19,7 @@ jupyter-client==5.3.4
 jupyter-core==4.6.0
 kiwisolver==1.1.0
 libroadrunner==1.5.4
-lxml==4.4.1
+lxml==4.9.1
 MarkupSafe==1.1.1
 matplotlib==3.1.1
 more-itertools==7.2.0