diff --git a/masquerade.module b/masquerade.module
index b50eb61..e65deb0 100644
--- a/masquerade.module
+++ b/masquerade.module
@@ -69,7 +69,7 @@ function masquerade_menu() {
       'title arguments' => array('@testuser' => $default_test_user->name),
       'page callback' => 'masquerade_switch_user_page',
       'page arguments' => array(2),
-  	  'access callback' => 'masquerade_access',
+      'access callback' => 'masquerade_access',
       'access arguments' => array('switch'),
       'type' => MENU_NORMAL_ITEM,
     );
@@ -364,7 +364,7 @@ function masquerade_user($op, &$edit, &$edit_user, $category = NULL) {
       break;
 
     case 'validate':
-      if ($category == 'account') {
+      if ($category == 'account' && isset($edit['masquerade_users'])) {
         $users = drupal_explode_tags($edit['masquerade_users']);
         foreach ($users as $user) {
           if (!user_load(array('name' => $user))) {