diff --git a/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
index 5648d27..a3fe908 100644
--- a/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
@@ -62,7 +62,11 @@ public function providerPlaceholders() {
         unset($token_render_array['#cache']);
       }
       $token = hash('sha1', serialize($token_render_array));
-      return '<drupal-render-placeholder callback="Drupal\Tests\Core\Render\PlaceholdersTest::callback" arguments="0=' . $args[0] . '" token="' . $token . '"></drupal-render-placeholder>';
+      return SafeMarkup::format('<drupal-render-placeholder callback="@callback" arguments="@arguments" token="@token"></drupal-render-placeholder>', [
+        '@callback' => 'Drupal\Tests\Core\Render\PlaceholdersTest::callback',
+        '@arguments' => '0=' . $args[0],
+        '@token' => $token,
+      ]);
     };
 
     $base_element_a1 = [
@@ -83,7 +87,7 @@ public function providerPlaceholders() {
       // @todo, see docblock
     ];
     $base_element_b = [
-      '#markup' => SafeMarkup::set($generate_placeholder_markup()),
+      '#markup' => $generate_placeholder_markup(),
       '#attached' => [
         'drupalSettings' => [
           'foo' => 'bar',
@@ -152,7 +156,7 @@ public function providerPlaceholders() {
     // - manually created
     // - cacheable
     $x = $base_element_b;
-    $x['#markup'] = SafeMarkup::set($generate_placeholder_markup($keys));
+    $x['#markup'] = $generate_placeholder_markup($keys);
     $x['#attached']['placeholders'] = [
       $generate_placeholder_markup($keys) => [
         '#lazy_builder' => ['Drupal\Tests\Core\Render\PlaceholdersTest::callback', $args],