diff --git a/ckan/logic/validators.py b/ckan/logic/validators.py
index 12cb0cbcb8f..b65febc0f25 100644
--- a/ckan/logic/validators.py
+++ b/ckan/logic/validators.py
@@ -175,6 +175,9 @@ def activity_type_exists(activity_type):
     'new group' : group_id_exists,
     'changed group' : group_id_exists,
     'deleted group' : group_id_exists,
+    'new organization' : group_id_exists,
+    'changed organization' : group_id_exists,
+    'deleted organization' : group_id_exists,
     'new related item': related_id_exists,
     'deleted related item': related_id_exists
     }