diff --git a/core/lib/Drupal/Core/Render/Element.php b/core/lib/Drupal/Core/Render/Element.php
index 83a8f97..9a3241f 100644
--- a/core/lib/Drupal/Core/Render/Element.php
+++ b/core/lib/Drupal/Core/Render/Element.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\Render;
 
+use Drupal\Component\Utility\String;
+
 /**
  * Deals with drupal render elements.
  */
@@ -84,7 +86,7 @@ public static function children(array &$elements, $sort = FALSE) {
         // Only trigger an error if the value is not null.
         // @see http://drupal.org/node/1283892
         elseif (isset($value)) {
-          trigger_error(t('"@key" is an invalid render array key', array('@key' => $key)), E_USER_ERROR);
+          trigger_error(String::format('"@key" is an invalid render array key', array('@key' => $key)), E_USER_ERROR);
         }
       }
     }
diff --git a/core/tests/Drupal/Tests/Core/Render/ElementTest.php b/core/tests/Drupal/Tests/Core/Render/ElementTest.php
index 2f55339..7d6e1bc 100644
--- a/core/tests/Drupal/Tests/Core/Render/ElementTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/ElementTest.php
@@ -5,7 +5,7 @@
  * Contains \Drupal\Tests\Core\Render\ElementTest.
  */
 
-namespace Drupal\Tests\Core\Render {
+namespace Drupal\Tests\Core\Render;
 
 use Drupal\Tests\UnitTestCase;
 use Drupal\Core\Render\Element;
@@ -157,13 +157,3 @@ public function providerTestSetAttributes() {
   }
 
 }
-
-}
-
-namespace {
-  if (!function_exists('t')) {
-    function t($string) {
-      return $string;
-    }
-  }
-}