diff --git a/modules/EcmInvoiceOuts/javascript/EcmInvoiceOuts3.js b/modules/EcmInvoiceOuts/javascript/EcmInvoiceOuts3.js
index 26d8381f..4383ab48 100644
--- a/modules/EcmInvoiceOuts/javascript/EcmInvoiceOuts3.js
+++ b/modules/EcmInvoiceOuts/javascript/EcmInvoiceOuts3.js
@@ -166,6 +166,11 @@ check_form = function(formname) {
             $(".loading_panel").css("display", "none");
             return false;
         }
+        if (items[index].price_netto == 0) {
+            alert("Niedopuszczalna, zerowa cena netto.");
+            $(".loading_panel").css("display", "none");
+            return false;
+        }
     }
     $("#total_netto").val($("#t_netto").val());
     $("#total_brutto").val($("#t_brutto").val());