diff --git a/username_validation.module b/username_validation.module
index 94290b7..b2ff919 100644
--- a/username_validation.module
+++ b/username_validation.module
@@ -43,12 +43,12 @@ function username_validation_menu() {
  * Implement hook_form_alter().
  */
 function username_validation_form_alter(&$form, &$form_state, $form_id) {
-  $username_config = variable_get('username_validation_config', array());
-  $username_validation_rule = variable_get('username_validation_rule', array());
-  $username_label = $username_config['user_label'];
-  $username_desc = $username_config['user_desc'];
-  $username_ajax = $username_validation_rule['ajax_validation'];
   if ($form_id == 'user_profile_form' || $form_id == 'user_register_form') {
+    $username_config = variable_get('username_validation_config', array());
+    $username_validation_rule = variable_get('username_validation_rule', array());
+    $username_label = isset($username_config['user_label']) ? $username_config['user_label'] : '';
+    $username_desc = isset($username_config['user_desc']) ? $username_config['user_desc'] : '';
+    $username_ajax = isset($username_validation_rule['ajax_validation']) ? $username_validation_rule['ajax_validation'] : '';
     //checking the configuration is enabled for ajax validation
     if ($username_ajax == 1) {
       $form['account']['name']['#suffix'] = "<div id='username-validation-ajax'></div>";