diff --git a/addons/l10n_es_edi_sii/models/account_edi_format.py b/addons/l10n_es_edi_sii/models/account_edi_format.py
index 4fc12283fda..5de42d2b41c 100644
--- a/addons/l10n_es_edi_sii/models/account_edi_format.py
+++ b/addons/l10n_es_edi_sii/models/account_edi_format.py
@@ -666,5 +666,5 @@ class AccountEdiFormat(models.Model):
                     'res_model': inv._name,
                     'res_id': inv.id,
                 })
-                res[inv] = {'attachment': attachment}
+                res[inv]['attachment'] = attachment
         return res