diff -u b/core/lib/Drupal/Core/Entity/Query/QueryBase.php b/core/lib/Drupal/Core/Entity/Query/QueryBase.php
--- b/core/lib/Drupal/Core/Entity/Query/QueryBase.php
+++ b/core/lib/Drupal/Core/Entity/Query/QueryBase.php
@@ -183,8 +183,8 @@
    *   An object holding a group of conditions.
    */
   protected function conditionGroupFactory($conjunction = 'AND') {
-    preg_match('/^(.*)\\\\/', get_class($this), $matches);
-    $class = $matches[1] .'\\Condition';
+    preg_match('/^.*\\\\/', get_class($this), $matches);
+    $class = $matches[0] .'Condition';
     return new $class($conjunction, $this);
   }
 
diff -u b/core/lib/Drupal/Core/Entity/Query/Sql/Query.php b/core/lib/Drupal/Core/Entity/Query/Sql/Query.php
--- b/core/lib/Drupal/Core/Entity/Query/Sql/Query.php
+++ b/core/lib/Drupal/Core/Entity/Query/Sql/Query.php
@@ -320,8 +320,8 @@
    * @return \Drupal\Core\Entity\Query\Sql\TablesInterface
    */
   public function getTables(SelectInterface $sql_query) {
-    preg_match('/^(.*)\\\\/', get_class($this), $matches);
-    $class = $matches[1] .'\\Tables';
+    preg_match('/^.*\\\\/', get_class($this), $matches);
+    $class = $matches[0] .'Tables';
     return new $class($sql_query);
   }
 
diff -u b/core/lib/Drupal/Core/Entity/Query/Sql/QueryFactory.php b/core/lib/Drupal/Core/Entity/Query/Sql/QueryFactory.php
--- b/core/lib/Drupal/Core/Entity/Query/Sql/QueryFactory.php
+++ b/core/lib/Drupal/Core/Entity/Query/Sql/QueryFactory.php
@@ -49,8 +49,8 @@
    *   The factored query.
    */
   public function get($entity_type, $conjunction, EntityManager $entity_manager) {
-    preg_match('/^(.*)\\\\/', get_class($this), $matches);
-    $class = $matches[1] .'\\Query';
+    preg_match('/^.*\\\\/', get_class($this), $matches);
+    $class = $matches[0] .'Query';
     return new $class($entity_type, $entity_manager, $conjunction, $this->connection);
   }
 
@@ -67,8 +67,8 @@
    *   The factored aggregation query.
    */
   public function getAggregate($entity_type, $conjunction, EntityManager $entity_manager) {
-    preg_match('/^(.*)\\\\/', get_class($this), $matches);
-    $class = $matches[1] .'\\QueryAggregate';
+    preg_match('/^.*\\\\/', get_class($this), $matches);
+    $class = $matches[0] .'QueryAggregate';
     return new $class($entity_type, $entity_manager, $conjunction, $this->connection);
   }