diff -u b/core/modules/system/src/Tests/Theme/TableTest.php b/core/modules/system/src/Tests/Theme/TableTest.php
--- b/core/modules/system/src/Tests/Theme/TableTest.php
+++ b/core/modules/system/src/Tests/Theme/TableTest.php
@@ -316,7 +316,7 @@
     $form = \Drupal::formBuilder()->getForm('\Drupal\form_test\Form\FormTestTableForm');
     $this->render($form);
     $this->assertEscaped('Update <em>kitten</em>');
-    $this->assertRaw('Update <em>flamingo</em>');
+    $this->assertRaw('Update my favourite fruit is <strong>bananas</strong>');
   }
 
 }
diff -u b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableForm.php b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableForm.php
--- b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableForm.php
+++ b/core/modules/system/tests/modules/form_test/src/Form/FormTestTableForm.php
@@ -36,7 +36,7 @@
     ];
     $form['table']['another_row'] = [
       'data' => [
-        '#title' => SafeString::create('<em>flamingo</em>'),
+        '#title' => $this->t('my favourite fruit is <strong>@fruit</strong>', ['@fruit' => 'bananas']),
         '#markup' => '<p>some more text</p>',
       ],
     ];