diff --git a/requirements.txt b/requirements.txt
index 01117a1..ca16edc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -15,7 +15,7 @@ image-slicer==0.1.1
 imagesize==1.1.0
 Jinja2==2.11.3
 jsonschema==2.5.1
-lxml==4.6.3
+lxml==4.9.1
 MarkupSafe==1.1.1
 numpy==1.16.2
 oauth2client==4.1.3