diff --git a/finance/views.py b/finance/views.py
index 2ee2551..ece22f6 100644
--- a/finance/views.py
+++ b/finance/views.py
@@ -195,11 +195,11 @@ class InvoiceDetailView(APIView):
             invoice.status = status
             invoice.key = key
 
-            if bill.check_pay() and (invoice.price < price):
+            if bill.check_pay() and (invoice.price < int(price)):
                 return Response("""Нельзя менять стоимость по счёту в большую сторону, 
                                    когда один из платежей оплачен""", status=400)
 
-            invoice.price = price
+            invoice.price = int(price)
             invoice.is_open = is_open
             invoice.comment = comment