diff --git a/core/modules/user/user.install b/core/modules/user/user.install
index 492f1e0..2a8a29c 100644
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -133,6 +133,13 @@ function user_schema() {
         'default' => '',
         'description' => 'E-mail address used for initial account creation.',
       ),
+      'anonymous' => array(
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+        'size' => 'tiny',
+        'description' => 'Whether this user is anonymous (1) or registered (0)',
+      ),
       'data' => array(
         'type' => 'blob',
         'not null' => FALSE,
@@ -599,5 +606,21 @@ function user_update_8009(&$sandbox) {
 }
 
 /**
+ * Add an anonymous flag to the user table.
+ */
+function user_update_8010(&$sandbox) {
+  db_add_field('users', 'anonymous', array(
+    'type' => 'int',
+    'not null' => TRUE,
+    'default' => 0,
+    'size' => 'tiny',
+    'description' => 'Whether this user is anonymous (1) or registered (0)',
+  ));
+
+  // Set user to be anonymous
+  db_query('UPDATE {users} SET anonymous = 1 WHERE uid = 0');
+}
+
+/**
  * @} End of "addtogroup updates-7.x-to-8.x".
  */
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index c064427..794857a 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -555,6 +555,25 @@ function user_is_blocked($name) {
 }
 
 /**
+ * Checks if a username is registered.
+ *
+ * @param $name
+ *   A string containing the name of the user.
+ *
+ * @return
+ *   True if the user is registered, false if they are anonymous.
+ */
+function user_is_registered($name) {
+  $result = db_select('users')
+    ->fields('users', array('name', 'uid'))
+    ->condition('name', db_like($name), 'LIKE')
+    ->condition('anonymous', 0)
+    ->execute()->fetchObject();
+
+  return ($result) ? TRUE : FALSE;
+}
+
+/**
  * Implements hook_permission().
  */
 function user_permission() {
@@ -1629,6 +1648,11 @@ function user_login_default_validators() {
  * A FAPI validate handler. Sets an error if supplied username has been blocked.
  */
 function user_login_name_validate($form, &$form_state) {
+  if (isset($form_state['values']['name']) && !user_is_registered($form_state['values']['name'])) {
+    // Not a registered account.
+    form_set_error('name', t('No registered account exists with the username %name', array('%name' => $form_state['values']['name'])));
+  }
+
   if (isset($form_state['values']['name']) && user_is_blocked($form_state['values']['name'])) {
     // Blocked in user administration.
     form_set_error('name', t('The username %name has not been activated or is blocked.', array('%name' => $form_state['values']['name'])));
@@ -1653,7 +1677,7 @@ function user_login_authenticate_validate($form, &$form_state) {
       $form_state['flood_control_triggered'] = 'ip';
       return;
     }
-    $account = db_query("SELECT * FROM {users} WHERE name = :name AND status = 1", array(':name' => $form_state['values']['name']))->fetchObject();
+    $account = db_query("SELECT * FROM {users} WHERE name = :name AND status = 1 AND anonymous = 0", array(':name' => $form_state['values']['name']))->fetchObject();
     if ($account) {
       if ($flood_config->get('uid_only')) {
         // Register flood events based on the uid only, so they apply for any