diff --git a/store/templates/buy.html b/store/templates/buy.html
index 9999c1245ad53e49f8872f44252080990dd8570c..2bf423a839fb692949412635c5edf306627ccf17 100644
--- a/store/templates/buy.html
+++ b/store/templates/buy.html
@@ -133,7 +133,7 @@
         // Check if id is a valid integer
         id = parseInt(id);
         if (isNaN(id)) {
-            error(null);
+            showError("Ungütiges Produkt");
             return;
         }
 
diff --git a/store/templates/charge.html b/store/templates/charge.html
index 0a0afd1120c70ff5e9746bab47d8962fed5beb4d..644fa413ae218cce694942091bf7ce3250322ba5 100644
--- a/store/templates/charge.html
+++ b/store/templates/charge.html
@@ -118,7 +118,7 @@
         var amount = $("#amount").val().replace(',', '.');
         amount = parseFloat(amount).toFixed(2);
         if (isNaN(amount)) {
-            error(null);
+            displayError("Ungültiger Betrag");
             return;
         }