diff --git a/addons/account_facturx/models/ir_actions_report.py b/addons/account_facturx/models/ir_actions_report.py
index 9e1d1f179a5..46028f40244 100644
--- a/addons/account_facturx/models/ir_actions_report.py
+++ b/addons/account_facturx/models/ir_actions_report.py
@@ -13,7 +13,7 @@ class IrActionsReport(models.Model):
     @api.multi
     def _post_pdf(self, save_in_attachment, pdf_content=None, res_ids=None):
         # OVERRIDE
-        if self.model == 'account.invoice' and (res_ids or len(res_ids) == 1):
+        if self.model == 'account.invoice' and res_ids and len(res_ids) == 1:
             invoice = self.env['account.invoice'].browse(res_ids)
             if invoice.type in ('out_invoice', 'out_refund') and invoice.state != 'draft':
                 xml_content = invoice._export_as_facturx_xml()