diff --git a/requirements.txt b/requirements.txt
index 63f4786..dea7efe 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-lxml >= 3.5.0, < 5
+lxml >= 4.1.1, < 5
 coveralls
 Jinja2
 signxml