diff --git a/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php b/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
index 6cbe5c9128..9c9b858e01 100644
--- a/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
+++ b/core/tests/Drupal/KernelTests/Setup/Commands/SetupDrupalTestScriptTest.php
@@ -152,6 +152,7 @@ public function testInstallInDifferentLanguage() {
     $this->assertEquals(0, $app_tester->getStatusCode());
 
     $result = json_decode($app_tester->getDisplay(), TRUE);
+    $db_prefix = substr($result['db_prefix'], 4);
     $http_client = new Client();
     $request = (new Request('GET', getenv('SIMPLETEST_BASE_URL') . '/test-page'))
       ->withHeader('User-Agent', trim($result['user_agent']));