diff --git a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
index 6d2604233327d9cfeaadd3813915cf845fe6d17e..a9ff4b136dcc6aac9f4e0db3b6944b12e889a865 100644
--- a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
+++ b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
@@ -409,8 +409,10 @@ protected function addJoin($type, $table, $join_condition, $langcode, $delta = N
    * @param string $table
    *   The table name.
    *
-   * @return array|bool
-   *   The table field mapping for the given table or FALSE if not available.
+   * @return array|false
+   *   An associative array of table field mapping for the given table, keyed by
+   *   columns name and values are just incrementing integers. If the table
+   *   mapping is not available, FALSE is returned.
    */
   protected function getTableMapping($table, $entity_type_id) {
     $storage = $this->entityManager->getStorage($entity_type_id);