--- a/src/pyams_form/security.py	Mon Sep 11 15:01:24 2017 +0200
+++ b/src/pyams_form/security.py	Tue Sep 12 11:16:41 2017 +0200
@@ -19,12 +19,13 @@
 from pyams_form.interfaces.form import IFormSecurityContext, IFormContextPermissionChecker
 
 # import packages
+from pyramid.decorator import reify
 
 
 class ProtectedFormObjectMixin(object):
     """Form object protected by a permission"""
 
-    @property
+    @reify
     def permission(self):
         registry = self.request.registry
         checker = None