core/modules/simpletest/src/WebTestBase.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index c0c36f9..44af34c 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -1844,7 +1844,7 @@ protected function drupalProcessAjaxResponse($content, array $ajax_response, arr
       }
       switch ($command['command']) {
         case 'settings':
-          NestedArray::mergeDeepArray([$drupal_settings, $command['settings']], TRUE);
+          $drupal_settings = NestedArray::mergeDeepArray([$drupal_settings, $command['settings']], TRUE);
           break;
 
         case 'insert':