diff --git a/greenmine/settings/common.py b/greenmine/settings/common.py
index 46ac235b..feae96da 100644
--- a/greenmine/settings/common.py
+++ b/greenmine/settings/common.py
@@ -301,6 +301,8 @@ AUTHENTICATION_BACKENDS = (
     'guardian.backends.ObjectPermissionBackend',
 )
 
+ANONYMOUS_USER_ID = -1
+
 HAYSTACK_CONNECTIONS = {
     'default': {
         'ENGINE': 'haystack.backends.whoosh_backend.WhooshEngine',