diff --git a/classes/Country.php b/classes/Country.php
index dd79ae914..c5b082620 100644
--- a/classes/Country.php
+++ b/classes/Country.php
@@ -373,6 +373,10 @@ class CountryCore extends ObjectModel
      */
     public function checkZipCode($zip_code)
     {
+        if (empty($this->zip_code_format)) {
+            return true;
+        }
+
         $zip_regexp = '/^'.$this->zip_code_format.'$/ui';
         $zip_regexp = str_replace(' ', '( |)', $zip_regexp);
         $zip_regexp = str_replace('-', '(-|)', $zip_regexp);
@@ -380,7 +384,7 @@ class CountryCore extends ObjectModel
         $zip_regexp = str_replace('L', '[a-zA-Z]', $zip_regexp);
         $zip_regexp = str_replace('C', $this->iso_code, $zip_regexp);
 
-        return (bool)preg_match($zip_regexp, (string) $zip_code);
+        return (bool)preg_match($zip_regexp, $zip_code);
     }
 
     public static function addModuleRestrictions(array $shops = array(), array $countries = array(), array $modules = array())
diff --git a/controllers/front/AuthController.php b/controllers/front/AuthController.php
index 41258d478..eee4a0616 100644
--- a/controllers/front/AuthController.php
+++ b/controllers/front/AuthController.php
@@ -548,10 +548,10 @@ class AuthControllerCore extends FrontController
 
                     $postcode = $$addresses_type->postcode;
                     /* Check zip code format */
-                    if ($country->zip_code_format && !$country->checkZipCode($postcode)) {
-                        $this->errors[] = sprintf(Tools::displayError('The Zip/Postal code you\'ve entered is invalid. It must follow this format: %s'), str_replace('C', $country->iso_code, str_replace('N', '0', str_replace('L', 'A', $country->zip_code_format))));
-                    } elseif (empty($postcode) && $country->need_zip_code) {
+                    if (empty($postcode) && $country->need_zip_code) {
                         $this->errors[] = Tools::displayError('A Zip / Postal code is required.');
+                    } elseif ($postcode && $country->zip_code_format && !$country->checkZipCode($postcode)) {
+                        $this->errors[] = sprintf(Tools::displayError('The Zip/Postal code you\'ve entered is invalid. It must follow this format: %s'), str_replace('C', $country->iso_code, str_replace('N', '0', str_replace('L', 'A', $country->zip_code_format))));
                     } elseif ($postcode && !Validate::isPostCode($postcode)) {
                         $this->errors[] = Tools::displayError('The Zip / Postal code is invalid.');
                     }