diff --git a/sru/almasru.py b/sru/almasru.py
index 41d0e17ac3e52c878cc9587687f827a2d3cf35bd..eeda6572329732887dc8f368e6169603c6f5c021 100644
--- a/sru/almasru.py
+++ b/sru/almasru.py
@@ -136,7 +136,7 @@ class RecordRetriever:
         return sru_url
 
     @staticmethod
-    def _response_to_xml(url):
+    def _response_to_xml(url: str) -> Element:
 
         response = request.urlopen(url).read()
         xml = fromstring(response)