diff --git a/setup.py b/setup.py
index 8dc40e9b..de72e509 100644
--- a/setup.py
+++ b/setup.py
@@ -85,6 +85,7 @@
             "plone.app.testing [robot]",
             "plone.testing",
             "robotsuite",
+            "lxml",
         ],
     },
 )