diff --git a/core/lib/Drupal/Core/Form/ConfirmFormBase.php b/core/lib/Drupal/Core/Form/ConfirmFormBase.php
index 03c7acd..1086d33 100644
--- a/core/lib/Drupal/Core/Form/ConfirmFormBase.php
+++ b/core/lib/Drupal/Core/Form/ConfirmFormBase.php
@@ -47,7 +47,8 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     $form['#title'] = $this->getQuestion();
 
     $form['#attributes']['class'][] = 'confirmation';
-    $form['description'] = array('#markup' => $this->getDescription());
+    $description = $this->getDescription();
+    $form['description'] = is_array($description) ? $description : array('#markup' => $description);
     $form[$this->getFormName()] = array('#type' => 'hidden', '#value' => 1);
 
     $form['actions'] = array('#type' => 'actions');
diff --git a/core/lib/Drupal/Core/Form/ConfirmFormInterface.php b/core/lib/Drupal/Core/Form/ConfirmFormInterface.php
index 0b67fd3..fe53785 100644
--- a/core/lib/Drupal/Core/Form/ConfirmFormInterface.php
+++ b/core/lib/Drupal/Core/Form/ConfirmFormInterface.php
@@ -31,7 +31,9 @@ public function getCancelUrl();
   /**
    * Returns additional text to display as a description.
    *
-   * @return string
+   * The text can be provided as a translated string or as a renderable array.
+   *
+   * @return string|array
    *   The form description.
    */
   public function getDescription();
diff --git a/core/modules/system/src/Tests/Form/ConfirmFormTest.php b/core/modules/system/src/Tests/Form/ConfirmFormTest.php
index 92a5aa9..1dbcbcb 100644
--- a/core/modules/system/src/Tests/Form/ConfirmFormTest.php
+++ b/core/modules/system/src/Tests/Form/ConfirmFormTest.php
@@ -50,6 +50,10 @@ function testConfirmForm() {
     $this->drupalGet('form-test/confirm-form-array-path');
     $this->clickLink(t('ConfirmFormArrayPathTestForm::getCancelText().'));
     $this->assertUrl('form-test/confirm-form', array('query' => array('destination' => 'admin/config')), "The form's complex cancel link was followed.");
+
+    // Test a confirm form, using a renderable array as description.
+    $this->drupalGet('form-test/confirm-form-extended');
+    $this->assertText(t('ConfirmFormTestForm::getDescription().'));
   }
 
   /**
diff --git a/core/modules/system/tests/modules/form_test/form_test.routing.yml b/core/modules/system/tests/modules/form_test/form_test.routing.yml
index d8c5833..b23c1a8 100644
--- a/core/modules/system/tests/modules/form_test/form_test.routing.yml
+++ b/core/modules/system/tests/modules/form_test/form_test.routing.yml
@@ -40,6 +40,13 @@ form_test.route6:
   requirements:
     _access: 'TRUE'
 
+form_test.route6_extended:
+  path: '/form-test/confirm-form-extended'
+  defaults:
+    _form: '\Drupal\form_test\ConfirmFormTestExtendedForm'
+  requirements:
+    _access: 'TRUE'
+
 form_test.route7:
   path: '/form-test/confirm-form-array-path'
   defaults:
diff --git a/core/modules/system/tests/modules/form_test/src/ConfirmFormTestExtendedForm.php b/core/modules/system/tests/modules/form_test/src/ConfirmFormTestExtendedForm.php
new file mode 100644
index 0000000..13f5f05
--- /dev/null
+++ b/core/modules/system/tests/modules/form_test/src/ConfirmFormTestExtendedForm.php
@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\form_test\ConfirmFormTestExtendedForm.
+ */
+
+namespace Drupal\form_test;
+
+/**
+ * Extends the test confirmation form.
+ */
+class ConfirmFormTestExtendedForm extends ConfirmFormTestForm {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDescription() {
+    return [
+      '#markup' => $this->t('ConfirmFormTestForm::getDescription().'),
+    ];
+  }
+
+}