diff --git a/invoice.py b/invoice.py
index c1dc25ab68..06f97c392a 100644
--- a/invoice.py
+++ b/invoice.py
@@ -485,9 +485,9 @@ class Invoice(ModelWorkflow, ModelSQL, ModelView):
                     continue
                 if line.second_currency.id == invoice.currency.id:
                     if line.debit - line.credit > Decimal('0.0'):
-                        amount_currency += line.amount_second_currency
+                        amount_currency += abs(line.amount_second_currency)
                     else:
-                        amount_currency -= line.amount_second_currency
+                        amount_currency -= abs(line.amount_second_currency)
                 else:
                     amount += line.debit - line.credit
             for line in invoice.payment_lines:
@@ -495,9 +495,9 @@ class Invoice(ModelWorkflow, ModelSQL, ModelView):
                     continue
                 if line.second_currency.id == invoice.currency.id:
                     if line.debit - line.credit > Decimal('0.0'):
-                        amount_currency += line.amount_second_currency
+                        amount_currency += abs(line.amount_second_currency)
                     else:
-                        amount_currency -= line.amount_second_currency
+                        amount_currency -= abs(line.amount_second_currency)
                 else:
                     amount += line.debit - line.credit
             if invoice.type in ('in_invoice', 'out_credit_note'):