diff --git a/core/lib/Drupal/Component/Render/FormattableMarkup.php b/core/lib/Drupal/Component/Render/FormattableMarkup.php
index cde8e86..261de41 100644
--- a/core/lib/Drupal/Component/Render/FormattableMarkup.php
+++ b/core/lib/Drupal/Component/Render/FormattableMarkup.php
@@ -65,7 +65,7 @@
  * @see \Drupal\Core\StringTranslation\PluralTranslatableMarkup
  * @see \Drupal\Component\Render\FormattableMarkup::placeholderFormat()
  */
-class FormattableMarkup implements MarkupInterface {
+class FormattableMarkup implements MarkupInterface, \Countable {
 
   /**
    * The arguments to replace placeholders with.
diff --git a/core/lib/Drupal/Component/Render/HtmlEscapedText.php b/core/lib/Drupal/Component/Render/HtmlEscapedText.php
index fd1e69d..f12e4e9 100644
--- a/core/lib/Drupal/Component/Render/HtmlEscapedText.php
+++ b/core/lib/Drupal/Component/Render/HtmlEscapedText.php
@@ -18,7 +18,7 @@
  *
  * @ingroup sanitization
  */
-class HtmlEscapedText implements MarkupInterface {
+class HtmlEscapedText implements MarkupInterface, \Countable {
 
   /**
    * The string to escape.
diff --git a/core/lib/Drupal/Component/Render/MarkupInterface.php b/core/lib/Drupal/Component/Render/MarkupInterface.php
index 9559437..65ab29a 100644
--- a/core/lib/Drupal/Component/Render/MarkupInterface.php
+++ b/core/lib/Drupal/Component/Render/MarkupInterface.php
@@ -35,7 +35,7 @@
  * @see sanitization
  * @see theme_render
  */
-interface MarkupInterface extends \JsonSerializable, \Countable {
+interface MarkupInterface extends \JsonSerializable {
 
   /**
    * Returns markup.
diff --git a/core/lib/Drupal/Core/Field/FieldFilteredMarkup.php b/core/lib/Drupal/Core/Field/FieldFilteredMarkup.php
index 4c164c4..8dcadca 100644
--- a/core/lib/Drupal/Core/Field/FieldFilteredMarkup.php
+++ b/core/lib/Drupal/Core/Field/FieldFilteredMarkup.php
@@ -24,7 +24,7 @@
  *
  * @see \Drupal\Core\Render\Markup
  */
-final class FieldFilteredMarkup implements MarkupInterface {
+final class FieldFilteredMarkup implements MarkupInterface, \Countable {
   use MarkupTrait;
 
   /**
diff --git a/core/lib/Drupal/Core/GeneratedLink.php b/core/lib/Drupal/Core/GeneratedLink.php
index 21d8b35..a612f66 100644
--- a/core/lib/Drupal/Core/GeneratedLink.php
+++ b/core/lib/Drupal/Core/GeneratedLink.php
@@ -17,7 +17,7 @@
  * Note: not to be confused with \Drupal\Core\Link, which is for passing around
  *   ungenerated links (typically link text + route name + route parameters).
  */
-class GeneratedLink extends BubbleableMetadata implements MarkupInterface {
+class GeneratedLink extends BubbleableMetadata implements MarkupInterface, \Countable {
 
   /**
    * The HTML string value containing a link.
diff --git a/core/lib/Drupal/Core/Render/Markup.php b/core/lib/Drupal/Core/Render/Markup.php
index b649b1a..c36d29f 100644
--- a/core/lib/Drupal/Core/Render/Markup.php
+++ b/core/lib/Drupal/Core/Render/Markup.php
@@ -25,6 +25,6 @@
  * @see \Twig_Markup
  * @see \Drupal\Component\Utility\SafeMarkup
  */
-final class Markup implements MarkupInterface {
+final class Markup implements MarkupInterface, \Countable {
   use MarkupTrait;
 }
diff --git a/core/lib/Drupal/Core/Template/Attribute.php b/core/lib/Drupal/Core/Template/Attribute.php
index d4f2b58..26a1793 100644
--- a/core/lib/Drupal/Core/Template/Attribute.php
+++ b/core/lib/Drupal/Core/Template/Attribute.php
@@ -347,11 +347,4 @@ public function jsonSerialize() {
     return (string) $this;
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function count() {
-    return count($this->storage);
-  }
-
 }
diff --git a/core/modules/filter/src/Render/FilteredMarkup.php b/core/modules/filter/src/Render/FilteredMarkup.php
index d7fe196..2abfac3 100644
--- a/core/modules/filter/src/Render/FilteredMarkup.php
+++ b/core/modules/filter/src/Render/FilteredMarkup.php
@@ -24,6 +24,6 @@
  *
  * @see \Drupal\Core\Render\Markup
  */
-final class FilteredMarkup implements MarkupInterface {
+final class FilteredMarkup implements MarkupInterface, \Countable {
   use MarkupTrait;
 }
diff --git a/core/modules/views/src/Render/ViewsRenderPipelineMarkup.php b/core/modules/views/src/Render/ViewsRenderPipelineMarkup.php
index 70d60dc..4532b9c 100644
--- a/core/modules/views/src/Render/ViewsRenderPipelineMarkup.php
+++ b/core/modules/views/src/Render/ViewsRenderPipelineMarkup.php
@@ -23,6 +23,6 @@
  *
  * @see \Drupal\Core\Render\Markup
  */
-final class ViewsRenderPipelineMarkup implements MarkupInterface {
+final class ViewsRenderPipelineMarkup implements MarkupInterface, \Countable {
   use MarkupTrait;
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/TwigMarkupInterfaceTest.php b/core/tests/Drupal/KernelTests/Core/Theme/TwigMarkupInterfaceTest.php
index 9150cba..551c658 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/TwigMarkupInterfaceTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/TwigMarkupInterfaceTest.php
@@ -8,12 +8,13 @@
 namespace Drupal\KernelTests\Core\Theme;
 
 use Drupal\Component\Render\FormattableMarkup;
+use Drupal\Component\Render\MarkupInterface;
+use Drupal\Component\Render\MarkupTrait;
 use Drupal\Core\GeneratedLink;
 use Drupal\Core\Render\RenderContext;
 use Drupal\Core\Render\Markup;
 use Drupal\Core\Site\Settings;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
-use Drupal\Core\Template\Attribute;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
@@ -49,10 +50,11 @@ public function providerTestMarkupInterfaceEmpty() {
       'empty FormattableMarkup' => ['', new FormattableMarkup('', ['@foo' => 'bar'])],
       'non-empty FormattableMarkup' => ['<span>bar</span>', new FormattableMarkup('@foo', ['@foo' => 'bar'])],
       'non-empty Markup' => ['<span>test</span>', Markup::create('test')],
-      'empty Attribute' => ['', new Attribute()],
-      'non-empty Attribute' => ['<span> id="test"</span>', new Attribute(['id' => 'test'])],
       'empty GeneratedLink' => ['', new GeneratedLink()],
-      'non-empty Attribute' => ['<span><a hef="http://www.example.com">test</a></span>', (new GeneratedLink())->setGeneratedLink('<a hef="http://www.example.com">test</a>')],
+      'non-empty GeneratedLink' => ['<span><a hef="http://www.example.com">test</a></span>', (new GeneratedLink())->setGeneratedLink('<a hef="http://www.example.com">test</a>')],
+      // Test objects that do not implement \Countable.
+      'empty SafeMarkupTestMarkup' => ['<span></span>', SafeMarkupTestMarkup::create('')],
+      'non-empty SafeMarkupTestMarkup' => ['<span>test</span>', SafeMarkupTestMarkup::create('test')],
     ];
   }
 
@@ -91,3 +93,20 @@ protected function renderObjectWithTwig($variable) {
   }
 
 }
+
+/**
+ * Implements MarkupInterface without implementing \Countable
+ */
+class SafeMarkupTestMarkup implements MarkupInterface {
+  use MarkupTrait;
+
+  /**
+   * Overrides MarkupTrait::create() to allow creation with empty strings.
+   */
+  public static function create($string) {
+    $object = new static();
+    $object->string = $string;
+    return $object;
+  }
+
+}
\ No newline at end of file