diff --git a/laterpay/__init__.py b/laterpay/__init__.py
index 17f32ed..31afa7f 100644
--- a/laterpay/__init__.py
+++ b/laterpay/__init__.py
@@ -2,7 +2,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, print_function
 
-import copy
 import json
 import logging
 import random
@@ -231,7 +230,8 @@ def _get_web_url(self,
                      transaction_reference=None,
                      consumable=False):
 
-        data = copy.copy(item_definition.data)
+        # filter out params with None value.
+        data = {k: v for k, v in item_definition.data.items() if v is not None}
 
         if use_jsevents:
             data['jsevents'] = 1
diff --git a/tests/test_client.py b/tests/test_client.py
index 4ff78eb..d60db70 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -85,6 +85,15 @@ def test_transaction_reference(self):
                 use_jsevents=True,
                 transaction_reference='123')
 
+    def test_get_web_url_has_no_none_params(self):
+        # item with expiry not set.
+        item = ItemDefinition(1, 'EUR20', 'DE19.0', 'http://help.me/', 'title')
+        url = self.lp.get_add_url(item)
+        self.assertFalse(
+            'expiry%3DNone' in url,
+            'expiry url param is "None". Should be omitted.',
+        )
+
 
 if __name__ == '__main__':
     unittest.main()