diff --git a/authentication/helpers/session.py b/authentication/helpers/session.py
index 91beebc..db8eb73 100644
--- a/authentication/helpers/session.py
+++ b/authentication/helpers/session.py
@@ -1,5 +1,6 @@
 from django.utils import timezone
 
 
-def session_expiry(start=timezone.now(), validity=timezone.timedelta(seconds=300)):
+def session_expiry(start=None, validity=timezone.timedelta(seconds=300)):
+    start = start or timezone.now()
     return start + validity
\ No newline at end of file