diff --git a/pillar/api/custom_field_validation.py b/pillar/api/custom_field_validation.py
index df52dfef..82a51730 100644
--- a/pillar/api/custom_field_validation.py
+++ b/pillar/api/custom_field_validation.py
@@ -159,7 +159,7 @@ class ValidateCustomFields(Validator):
             # validator at all.
             return
 
-        if self._id is None:
+        if self.document_id is None:
             # This is a creation call, in which case this validator shouldn't run.
             return