diff --git a/controllers/front/GuestTrackingController.php b/controllers/front/GuestTrackingController.php
index ab05a2876..e7017e12f 100644
--- a/controllers/front/GuestTrackingController.php
+++ b/controllers/front/GuestTrackingController.php
@@ -92,10 +92,11 @@ class GuestTrackingControllerCore extends FrontController
                     $customer = new Customer((int)$order->id_customer);
                     if (!Validate::isLoadedObject($customer)) {
                         $this->errors[] = Tools::displayError('Invalid customer');
-                    } elseif (!Tools::getValue('password')) {
+                    } elseif (!Tools::getValue('password')
+                        || !Validate::isPasswd(Tools::getValue('password')
+                    )) {
                         $this->errors[] = Tools::displayError('Invalid password.');
                     } elseif (!$customer->transformToCustomer($this->context->language->id, Tools::getValue('password'))) {
-                        // @todo clarify error message
                         $this->errors[] = Tools::displayError('An error occurred while transforming a guest into a registered customer.');
                     } else {
                         $this->context->smarty->assign('transformSuccess', true);
diff --git a/controllers/front/OrderOpcController.php b/controllers/front/OrderOpcController.php
index 465c6a7ca..2cd2a223c 100644
--- a/controllers/front/OrderOpcController.php
+++ b/controllers/front/OrderOpcController.php
@@ -173,7 +173,9 @@ class OrderOpcControllerCore extends ParentOrderController
 
                             if (!count($this->errors)) {
                                 $customer = new Customer($this->context->customer->id);
-                                if ($customer->transformToCustomer($this->context->language->id, $passwd)) {
+                                if (!$customer->isGuest()) {
+                                    $this->errors[] = Tools::displayError('This account is already registered as a customer.');
+                                } else if ($customer->transformToCustomer($this->context->language->id, $passwd)) {
                                     $this->context->updateCustomer($customer);
                                 } else {
                                     $this->errors[] = Tools::displayError('An error occurred while transforming your account into a registered customer.');