diff --git a/phenopipe-web/requirements.txt b/phenopipe-web/requirements.txt
index 9a5ed07..5a60fff 100644
--- a/phenopipe-web/requirements.txt
+++ b/phenopipe-web/requirements.txt
@@ -35,7 +35,7 @@ iso8601==0.1.11
 itsdangerous==0.24
 jdcal==1.3
 Jinja2==2.8
-lxml==3.6.4
+lxml==4.9.1
 Mako==1.0.6
 MarkupSafe==0.23
 openpyxl==2.4.8