diff --git a/core/lib/Drupal/Core/Path/AliasManager.php b/core/lib/Drupal/Core/Path/AliasManager.php
index d1e2797..b2d2d7b 100644
--- a/core/lib/Drupal/Core/Path/AliasManager.php
+++ b/core/lib/Drupal/Core/Path/AliasManager.php
@@ -327,14 +327,8 @@ protected function pathAliasWhitelistRebuild($source = NULL) {
    *   TRUE if alias exists, false otherwise.
    */
   public function checkAliasExists($pid, $alias, $langcode) {
-    $query = $this->connection->select('url_alias', 'u')
-      ->fields('u', array('pid'))
-      ->condition(db_and()
-        ->condition('pid', $pid, '<>')
-        ->condition('alias', $alias)
-        ->condition('langcode', $langcode))
-      ->range(0,1);
-    return (bool) $query->execute()->fetchField();
+    $query = 'SELECT pid FROM {url_alias} WHERE pid != :pid AND alias = :alias AND langcode = :langcode LIMIT 1';
+    return (bool) $this->connection->query($query, array(':pid' => $pid, ':alias' => $alias, ':langcode' => $langcode))->fetchField();
   }
 
 }
diff --git a/core/modules/path/lib/Drupal/path/Form/EditForm.php b/core/modules/path/lib/Drupal/path/Form/EditForm.php
index 782adc2..45b0604 100644
--- a/core/modules/path/lib/Drupal/path/Form/EditForm.php
+++ b/core/modules/path/lib/Drupal/path/Form/EditForm.php
@@ -75,7 +75,17 @@ public function getFormID() {
   }
 
   /**
-   * {@inheritdoc}
+   * Form constructor.
+   *
+   * @param array $form
+   *   An associative array containing the structure of the form.
+   * @param array $form_state
+   *   An associative array containing the current state of the form.
+   * @param int $pid
+   *   Optional path id. Can be omitted when adding a new path alias.
+   *
+   * @return array
+   *   The form structure.
    */
   public function buildForm(array $form, array &$form_state, $pid = NULL) {
     $path_alias = $this->path->load(array('pid' => $pid));
diff --git a/core/modules/path/lib/Drupal/path/Form/PathAdminFilterForm.php b/core/modules/path/lib/Drupal/path/Form/PathAdminFilterForm.php
index 05575cf..793cf93 100644
--- a/core/modules/path/lib/Drupal/path/Form/PathAdminFilterForm.php
+++ b/core/modules/path/lib/Drupal/path/Form/PathAdminFilterForm.php
@@ -22,7 +22,17 @@ public function getFormID() {
   }
 
   /**
-   * {@inheritdoc}
+   * Form constructor.
+   *
+   * @param array $form
+   *   An associative array containing the structure of the form.
+   * @param array $form_state
+   *   An associative array containing the current state of the form.
+   * @param string $alias
+   *   A string containing a keyword for searching aliases.
+   *
+   * @return array
+   *   The form structure.
    */
   public function buildForm(array $form, array &$form_state, $alias = NULL) {
     $form['#attributes'] = array(