diff --git a/requirements.txt b/requirements.txt
index 61b4be3..1f70a4f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,4 @@
-lxml
-zeep
+lxml >= 3.5.0, < 4
 nose
 mock
 coveralls
@@ -15,4 +14,4 @@ cryptography >= 1.8, < 3
 pyOpenSSL >= 16.0.0, < 17
 certifi >= 2015.11.20.1
 reportlab
-pytz
\ No newline at end of file
+pytz