diff --git a/djangorestframework/permissions.py b/djangorestframework/permissions.py
index 0de1d16d8..cd28438d1 100644
--- a/djangorestframework/permissions.py
+++ b/djangorestframework/permissions.py
@@ -80,6 +80,9 @@ class IsAdminUser(BasePermission):
 class IsModelInstanceOwnerOrIsAnonReadOnly(BasePermission):
     """
     The request is authenticated as the owner of the model instance, or is a read-only request.
+
+    In order to determine the owner the model has to provide a .get_owner() function,
+    otherwise the permission will be denied. 
     """
 
     def check_permission(self, user):