diff --git a/roost_backend/serializers.py b/roost_backend/serializers.py
index 28339d8..7549c12 100644
--- a/roost_backend/serializers.py
+++ b/roost_backend/serializers.py
@@ -73,7 +73,7 @@ class KerberosCredentialsSerializer(serializers.Serializer):
     authtime = serializers.IntegerField()
     starttime = serializers.IntegerField()
     endtime = serializers.IntegerField()
-    renew_till = serializers.IntegerField(required=False)
+    renew_till = serializers.IntegerField(required=False, default=0)
     srealm = serializers.CharField()
     sname = _InlineNameSerializer()
 
diff --git a/roost_backend/utils/kerberos.py b/roost_backend/utils/kerberos.py
index 38bc367..f240dbd 100644
--- a/roost_backend/utils/kerberos.py
+++ b/roost_backend/utils/kerberos.py
@@ -93,7 +93,7 @@ def verify_same_princ(client):
     kcreds.times.authtime = creds['authtime'] // 1000
     kcreds.times.starttime = creds['starttime'] // 1000
     kcreds.times.endtime = creds['endtime'] // 1000
-    kcreds.times.renew_till = creds.get('renew_till', 0) // 1000
+    kcreds.times.renew_till = creds['renew_till'] // 1000
     kcreds.is_skey = False
 
     # This makes roost's python sad. Add a null check there before dereferencing.