diff -u b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
--- b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Tests\Core\Render;
 
+use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Render\Element;
 use Drupal\Core\Cache\Cache;
@@ -69,7 +70,7 @@
       if (is_array($cache_keys)) {
         $token_render_array['#cache']['keys'] = $cache_keys;
       }
-      $token = hash('sha256', serialize($token_render_array));
+      $token = Crypt::hashBase64(serialize($token_render_array));
       // \Drupal\Core\Render\Markup::create() is necessary as the render
       // system would mangle this markup. As this is exactly what happens at
       // runtime this is a valid use-case.
@@ -616,7 +617,7 @@
 
     $this->setUpRequest('GET');
 
-    $token = hash('sha256', serialize($expected_placeholder_render_array));
+    $token = Crypt::hashBase64(serialize($expected_placeholder_render_array));
     $placeholder_callback = $expected_placeholder_render_array['#lazy_builder'][0];
     $expected_placeholder_markup = '<drupal-render-placeholder callback="' . $placeholder_callback . '" arguments="0=' . $args[0] . '" token="' . $token . '"></drupal-render-placeholder>';
     $this->assertSame($expected_placeholder_markup, Html::normalize($expected_placeholder_markup), 'Placeholder unaltered by Html::normalize() which is used by FilterHtmlCorrector.');