diff --git a/requirements.txt b/requirements.txt
index 195d0c6..9a6ba3a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,7 +17,7 @@ idna==2.9
 itsdangerous==1.1.0
 Jinja2==2.11.1
 kiwisolver==1.2.0
-lxml==4.3.1
+lxml==4.9.1
 MarkupSafe==1.1.1
 matplotlib==3.2.1
 numpy==1.16.1