diff --git a/l10n_it_fatturapa_in/wizard/wizard_import_fatturapa.py b/l10n_it_fatturapa_in/wizard/wizard_import_fatturapa.py
index 4147127d25cb..cf6d3186bfee 100644
--- a/l10n_it_fatturapa_in/wizard/wizard_import_fatturapa.py
+++ b/l10n_it_fatturapa_in/wizard/wizard_import_fatturapa.py
@@ -1130,7 +1130,8 @@ def set_roundings(self, FatturaBody, invoice):
                     _('Round up and down tax is not set')
                 )
 
-            line_sequence = max(invoice.invoice_line_ids.mapped('sequence'))
+            # invoice may have no lines at all if imported with minimum detail level
+            line_sequence = max(invoice.invoice_line_ids.mapped('sequence') or [0])
             line_vals = []
             for summary in FatturaBody.DatiBeniServizi.DatiRiepilogo:
                 to_round = float(summary.Arrotondamento or 0.0)