diff --git a/modules/account_invoice/invoice.py b/modules/account_invoice/invoice.py
index fa790262c2..b27b970d03 100644
--- a/modules/account_invoice/invoice.py
+++ b/modules/account_invoice/invoice.py
@@ -1432,6 +1432,8 @@ class Invoice(Workflow, ModelSQL, ModelView, TaxableMixin, InvoiceReportMixin):
         default.setdefault('total_amount_cache', None)
         default.setdefault('untaxed_amount_cache', None)
         default.setdefault('tax_amount_cache', None)
+        default.setdefault('validated_by')
+        default.setdefault('posted_by')
         return super(Invoice, cls).copy(invoices, default=default)
 
     @classmethod