diff --git a/django_rules/models.py b/django_rules/models.py
index 3671bc8..1691a69 100644
--- a/django_rules/models.py
+++ b/django_rules/models.py
@@ -40,7 +40,7 @@ def save(self, *args, **kwargs):
         # If field_name does not exist a ValidationError is raised
         if not hasattr(self.content_type.model_class(), self.field_name):
             # Search within attributes field names
-            if not (self.field_name in self.content_type.model_class()._meta.get_all_field_names()):
+            if not (self.field_name in self.content_type.model_class()._meta.get_fields()):
                 raise NonexistentFieldName("Could not create rule: field_name %s of rule %s does not exist in model %s" %
                                             (self.field_name, self.codename, self.content_type.model))
         else: