diff --git a/access_code.module b/access_code.module
index 612e0e3fa26f0b707d63e43f7d429a225671be26..6af483e1eaf35a7121d7dd1050912673320ba05c 100644
--- a/access_code.module
+++ b/access_code.module
@@ -129,7 +129,7 @@ function access_code_user_profile_form_validate($form, &$form_state) {
     form_set_error('user_access_code', t('The access code can not be longer than 20 characters.'));
   }
 
-  if (drupal_strlen($form_state['values']['access_code']) < 4) {
+  if (!empty($form_state['values']['access_code']) && drupal_strlen($form_state['values']['access_code']) < 4) {
     form_set_error('user_access_code', t('Please choose an access code that is at least 4 characters long. A short access code poses security risk.'));
   }