diff --git a/core/lib/Drupal/Core/Test/Comparator/MarkupInterfaceComparator.php b/core/lib/Drupal/Core/Test/Comparator/MarkupInterfaceComparator.php
index 73dc1ded98..7b3a390e01 100644
--- a/core/lib/Drupal/Core/Test/Comparator/MarkupInterfaceComparator.php
+++ b/core/lib/Drupal/Core/Test/Comparator/MarkupInterfaceComparator.php
@@ -3,7 +3,6 @@
 namespace Drupal\Core\Test\Comparator;
 
 use Drupal\Component\Render\MarkupInterface;
-use Drupal\Tests\AssertHelperTrait;
 use SebastianBergmann\Comparator\Comparator;
 
 /**
@@ -11,8 +10,6 @@
  */
 class MarkupInterfaceComparator extends Comparator {
 
-  use AssertHelperTrait;
-
   /**
    * {@inheritdoc}
    */
@@ -24,25 +21,10 @@ public function accepts($expected, $actual) {
       return FALSE;
     }
     // When either expected or actual are MarkupInterface objects, we take over
-    // and convert to strings before comparing. This also happens when the
-    // values to compare are arrays where at least a MarkupInterface object is
-    // present, in which case the object is converted to string.
+    // and convert to strings before comparing.
     if ($expected instanceof MarkupInterface || $actual instanceof MarkupInterface) {
       return TRUE;
     }
-    foreach ([$expected, $actual] as $value) {
-      if (is_array($value)) {
-        $markup_item_found = FALSE;
-        array_walk_recursive($value, function ($item, &$markup_item_found) {
-          if ($item instanceof MarkupInterface) {
-            $markup_item_found = TRUE;
-          }
-        });
-        if ($markup_item_found) {
-          return TRUE;
-        }
-      }
-    }
     return FALSE;
   }
 
@@ -50,8 +32,8 @@ public function accepts($expected, $actual) {
    * {@inheritdoc}
    */
   public function assertEquals($expected, $actual, $delta = 0.0, $canonicalize = false, $ignoreCase = false, array &$processed = []) {
-    $expected_safe = static::castSafeStrings($expected);
-    $actual_safe = static::castSafeStrings($actual);
+    $expected_safe = (string) $expected;
+    $actual_safe = (string) $actual;
 
     $comparator = $this->factory->getComparatorFor($expected_safe, $actual_safe);
     $comparator->assertEquals($expected_safe, $actual_safe, $delta, $canonicalize, $ignoreCase, $processed);