diff --git a/core/modules/user/src/Controller/UserController.php b/core/modules/user/src/Controller/UserController.php
index 772884b..81e439b 100644
--- a/core/modules/user/src/Controller/UserController.php
+++ b/core/modules/user/src/Controller/UserController.php
@@ -163,7 +163,7 @@ public function userPage() {
    *   NULL.
    */
   public function userTitle(UserInterface $user = NULL) {
-    return $user ? ['#markup' => $user->getUsername(), '#allowed_tags' => Xss::getHtmlTagList()] : '';
+    return $user ? ['#markup' => $user->getDisplayName(), '#allowed_tags' => Xss::getHtmlTagList()] : '';
   }
 
   /**
diff --git a/core/modules/user/src/Tests/UserDisplayNameTest.php b/core/modules/user/src/Tests/UserDisplayNameTest.php
new file mode 100644
index 0000000..69df44e
--- /dev/null
+++ b/core/modules/user/src/Tests/UserDisplayNameTest.php
@@ -0,0 +1,69 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\user\Tests\UserDisplayNameTest.
+ */
+
+namespace Drupal\user\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests that display name is shown everywhere.
+ *
+ * @group user
+ */
+class UserDisplayNameTest extends WebTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = [
+    'user',
+    'user_hooks_test',
+  ];
+
+  /**
+   * An authenticated user to use for testing.
+   *
+   * @var \Drupal\user\UserInterface
+   */
+  protected $account;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $permissions = [
+      'access user profiles',
+      'administer users',
+    ];
+
+    $this->account = $this->drupalCreateUser($permissions);
+  }
+
+  /**
+   * Test display name.
+   */
+  function testDisplayName() {
+    // Set to test the altered username.
+    \Drupal::state()->set('user_hooks_test_user_format_name_alter', TRUE);
+
+    // We must login after the alter hook as been enabled or the username will
+    // be shown instead of the display name.
+    $this->drupalLogin($this->account);
+
+    // Test if the altered display name is properly shown on pages.
+    $this->drupalGet('user/' . $this->account->id());
+    $this->assertRaw($this->account->getDisplayName(), 'User view page shows altered user display name.');
+
+    $this->drupalGet('user/' . $this->account->id() . '/edit');
+    $this->assertRaw($this->account->getDisplayName(), 'User edit page shows altered user display name.');
+  }
+
+}
diff --git a/core/modules/user/src/Tests/UserEntityCallbacksTest.php b/core/modules/user/src/Tests/UserEntityCallbacksTest.php
index ce7726a..c6704e6 100644
--- a/core/modules/user/src/Tests/UserEntityCallbacksTest.php
+++ b/core/modules/user/src/Tests/UserEntityCallbacksTest.php
@@ -38,6 +38,9 @@ class UserEntityCallbacksTest extends WebTestBase {
    */
   protected $anonymous;
 
+  /**
+   * {@inheritdoc}
+   */
   protected function setUp() {
     parent::setUp();
 
@@ -56,7 +59,7 @@ function testLabelCallback() {
     $this->config('user.settings')->set('anonymous', $name)->save();
     $this->assertEqual($this->anonymous->label(), $name, 'The variable anonymous should be used for name of uid 0');
     $this->assertEqual($this->anonymous->getDisplayName(), $name, 'The variable anonymous should be used for display name of uid 0');
-    $this->assertEqual($this->anonymous->getUserName(), '', 'The raw anonymous user name should be empty string');
+    $this->assertEqual($this->anonymous->getUsername(), '', 'The raw anonymous user name should be empty string');
 
     // Set to test the altered username.
     \Drupal::state()->set('user_hooks_test_user_format_name_alter', TRUE);