diff --git a/mellon/views.py b/mellon/views.py
index e5d6e5b..7bab9a3 100644
--- a/mellon/views.py
+++ b/mellon/views.py
@@ -338,9 +338,10 @@ class LoginView(ProfileMixin, LogMixin, View):
             # configure requested AuthnClassRef
             authn_classref = utils.get_setting(idp, 'AUTHN_CLASSREF')
             if authn_classref:
+                authn_classref = tuple([str(x) for x in authn_classref])
                 req_authncontext = lasso.Samlp2RequestedAuthnContext()
                 authn_request.requestedAuthnContext = req_authncontext
-                req_authncontext.authnContextClassRef = tuple(authn_classref)
+                req_authncontext.authnContextClassRef = authn_classref
             self.set_next_url(next_url)
             login.buildAuthnRequestMsg()
         except lasso.Error, e:
diff --git a/tests/test_views.py b/tests/test_views.py
index bb42316..42bfd8f 100644
--- a/tests/test_views.py
+++ b/tests/test_views.py
@@ -198,8 +198,8 @@ def test_sp_initiated_login_chosen(private_settings, client):
 def test_sp_initiated_login_requested_authn_context(private_settings, client):
     private_settings.MELLON_IDENTITY_PROVIDERS = [{
         'METADATA': open('tests/metadata.xml').read(),
-        'AUTHN_CLASSREF': ['urn:be:fedict:iam:fas:citizen:eid',
-                           'urn:be:fedict:iam:fas:citizen:token'],
+        'AUTHN_CLASSREF': [u'urn:be:fedict:iam:fas:citizen:eid',
+                           u'urn:be:fedict:iam:fas:citizen:token'],
     }]
     response = client.get('/login/')
     assert response.status_code == 302