diff --git a/src/lib/python/isc/ddns/tests/session_tests.py b/src/lib/python/isc/ddns/tests/session_tests.py
index 2abee9068759f631cafb1c240e2bc7d34bd206d0..e5b85d7b9c9dba54b3c3f60da8e657fb5b07e7a2 100644
--- a/src/lib/python/isc/ddns/tests/session_tests.py
+++ b/src/lib/python/isc/ddns/tests/session_tests.py
@@ -245,7 +245,7 @@ class SessionTest(unittest.TestCase):
 
     def test_check_prerequisite_exists_value(self):
         method = self.__session._UpdateSession__prereq_rrset_exists_value
-        
+
         rrset = isc.dns.RRset(isc.dns.Name("www.example.org"),
                               isc.dns.RRClass.IN(), isc.dns.RRType.A(),
                               isc.dns.RRTTL(0))