diff --git a/src/saml2/entity.py b/src/saml2/entity.py
index 171a1a1..6c2adf1 100644
--- a/src/saml2/entity.py
+++ b/src/saml2/entity.py
@@ -339,7 +339,7 @@ class Entity(HTTPBase):
             mid = msg.id
 
         try:
-            to_sign.append([(class_name(msg), mid)])
+            to_sign += [(class_name(msg), mid)]
         except AttributeError:
             to_sign = [(class_name(msg), mid)]
 
@@ -451,7 +451,7 @@ class Entity(HTTPBase):
         self._add_info(response, **kwargs)
 
         if sign:
-            self.sign(response, to_sign=to_sign)
+            return self.sign(response, to_sign=to_sign)
         elif to_sign:
             return signed_instance_factory(response, self.sec, to_sign)
         else: