diff --git a/test/acceptance/requirements.txt b/test/acceptance/requirements.txt
index 28e147b0..1c405d63 100644
--- a/test/acceptance/requirements.txt
+++ b/test/acceptance/requirements.txt
@@ -18,7 +18,7 @@ h11==0.12.0
 idna==3.3
 itsdangerous==2.0.1
 Jinja2==3.0.3
-lxml==4.6.4
+lxml==4.9.1
 MarkupSafe==2.0.1
 outcome==1.1.0
 OWSLib @ git+https://github.com/geopython/OWSLib@4a73688c2073404a3e1c0ce6cc752865e111b65f