diff --git a/modules/purchase/purchase.py b/modules/purchase/purchase.py
index 68d560e..00b8180 100755
--- a/modules/purchase/purchase.py
+++ b/modules/purchase/purchase.py
@@ -1028,7 +1028,7 @@ class Purchase(
             forex_rate = invoice.get_forex()
             if forex_rate:
                 invoice.selection_rate = 'forex'
-                invoice.on_change_with_rate()
+                invoice.rate = invoice.on_change_with_rate()
                 Invoice.save([invoice])
             purchase.copy_resources_to(invoice)
             if len(invoices)==1: