diff --git a/oauth/base.py b/oauth/base.py
index 15a82c1c4..ee290bbf5 100644
--- a/oauth/base.py
+++ b/oauth/base.py
@@ -1,6 +1,9 @@
 import logging
 import urllib
 
+from abc import ABCMeta, abstractmethod
+from six import add_metaclass
+
 from util import get_app_url
 
 logger = logging.getLogger(__name__)
@@ -13,36 +16,43 @@ class OAuthGetUserInfoException(Exception):
   """ Exception raised if a call to get user information fails. """
   pass
 
+@add_metaclass(ABCMeta)
 class OAuthService(object):
   """ A base class for defining an external service, exposed via OAuth. """
   def __init__(self, config, key_name):
     self.key_name = key_name
     self.config = config.get(key_name) or {}
 
+  @abstractmethod
   def service_id(self):
     """ The internal ID for this service. Must match the URL portion for the service, e.g. `github`
     """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def service_name(self):
     """ The user-readable name for the service, e.g. `GitHub`"""
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def token_endpoint(self):
     """ The endpoint at which the OAuth code can be exchanged for a token. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def user_endpoint(self):
     """ The endpoint at which user information can be looked up. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def validate_client_id_and_secret(self, http_client, app_config):
     """ Performs validation of the client ID and secret, raising an exception on failure. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def authorize_endpoint(self):
     """ Endpoint for authorization. """
-    raise NotImplementedError
+    pass
 
   def requires_form_encoding(self):
     """ Returns True if form encoding is necessary for the exchange_code_for_token call. """
diff --git a/oauth/login.py b/oauth/login.py
index 268d030f7..55c94be69 100644
--- a/oauth/login.py
+++ b/oauth/login.py
@@ -1,5 +1,8 @@
 import logging
 
+from abc import ABCMeta, abstractmethod
+from six import add_metaclass
+
 import features
 
 from oauth.base import OAuthService, OAuthExchangeCodeException, OAuthGetUserInfoException
@@ -10,33 +13,41 @@ class OAuthLoginException(Exception):
   """ Exception raised if a login operation fails. """
   pass
 
+
+@add_metaclass(ABCMeta)
 class OAuthLoginService(OAuthService):
   """ A base class for defining an OAuth-compliant service that can be used for, amongst other
       things, login and authentication. """
 
+  @abstractmethod
   def login_enabled(self):
     """ Returns true if the login service is enabled. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def get_login_service_id(self, user_info):
     """ Returns the internal ID for the given user under this login service. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def get_login_service_username(self, user_info):
     """ Returns the username for the given user under this login service. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def get_verified_user_email(self, app_config, http_client, token, user_info):
     """ Returns the verified email address for the given user, if any or None if none. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def get_icon(self):
     """ Returns the icon to display for this login service. """
-    raise NotImplementedError
+    pass
 
+  @abstractmethod
   def get_login_scopes(self):
     """ Returns the list of scopes for login for this service. """
-    raise NotImplementedError
+    pass
 
   def service_verify_user_info_for_login(self, app_config, http_client, token, user_info):
     """ Performs service-specific verification of user information for login. On failure, a service