diff --git a/core/lib/Drupal/Core/Database/StatementPrefetch.php b/core/lib/Drupal/Core/Database/StatementPrefetch.php
index f860a9f..83b8cf6 100644
--- a/core/lib/Drupal/Core/Database/StatementPrefetch.php
+++ b/core/lib/Drupal/Core/Database/StatementPrefetch.php
@@ -284,7 +284,7 @@ class StatementPrefetch implements Iterator, StatementInterface {
         case PDO::FETCH_OBJ:
           return (object) $this->currentRow;
         case PDO::FETCH_CLASS | PDO::FETCH_CLASSTYPE:
-          $class_name = array_unshift($this->currentRow);
+          array_unshift($class_name, $this->currentRow);
           // Deliberate no break.
         case PDO::FETCH_CLASS:
           if (!isset($class_name)) {