diff --git a/issue6253.diff b/issue6253.diff
index 870c715..302cedc 100644
--- a/issue6253.diff
+++ b/issue6253.diff
@@ -17,7 +17,7 @@ diff -r 6c85f394741c invoice.py
          pattern.setdefault('fiscalyear', fiscalyear.id)
          pattern.setdefault('period', period.id)
          invoice_type = self.type
--        if (all(l.amount < 0 for l in self.lines if l.product)
+-        if (all(l.amount <= 0 for l in self.lines if l.product)
 -                and self.total_amount < 0):
 -            invoice_type += '_credit_note'
 -        else: