diff --git a/vendor/plugins/access_control/lib/role.rb b/vendor/plugins/access_control/lib/role.rb
index 9d527cf..62d9079 100644
--- a/vendor/plugins/access_control/lib/role.rb
+++ b/vendor/plugins/access_control/lib/role.rb
@@ -30,7 +30,7 @@ class Role < ActiveRecord::Base
 
   before_destroy :check_for_system_defined_role
   def check_for_system_defined_role
-    ! system
+    ! self.system
   end
 
   protected
--
libgit2 0.21.2