diff --git a/Checkout.php b/Checkout.php
index 3108298..010c7e6 100644
--- a/Checkout.php
+++ b/Checkout.php
@@ -195,7 +195,7 @@ class Checkout extends Component
                 }
             }
             if ($config['name'] === 'hostname') {
-                $validationRules = ['required', 'string', 'regex:/^[a-zA-Z0-9]+\.[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)*$/'];
+                $validationRules = ['required', 'string', 'max:18', 'regex:/^[a-zA-Z0-9]+\.[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)*$/'];
             }
             if (count($validationRules) > 0) {
                 $rules["checkoutConfig.{$config['name']}"] = $validationRules;