diff --git a/requirements.txt b/requirements.txt
index 2f85189..3520273 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -11,6 +11,7 @@ odfpy==1.4.1
 requests==2.31.0
 jinja2==3.1.2
 jsonref==1.1.0
+lxml==5.1.0
 pyld==2.0.3
 pynacl==1.5.0
 more-itertools==10.1.0