diff --git a/src/Form/HelpLockForm.php b/src/Form/HelpLockForm.php
index 9d1ec48..9979a6e 100644
--- a/src/Form/HelpLockForm.php
+++ b/src/Form/HelpLockForm.php
@@ -4,7 +4,10 @@ namespace Drupal\config_help\Form;
 
 use Drupal\Core\Entity\EntityConfirmFormBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
 use Drupal\Core\Url;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Provides a form for confirming locking of a help topic.
@@ -12,6 +15,36 @@ use Drupal\Core\Url;
 class HelpLockForm extends EntityConfirmFormBase {
 
   /**
+   * The Messenger service.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Constructs the help topic lock form.
+   *
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   The messenger service.
+   * @param TranslationInterface $string_translation
+   *   The translation manager.
+   */
+  public function __construct(MessengerInterface $messenger, TranslationInterface $string_translation) {
+    $this->messenger = $messenger;
+    $this->stringTranslation = $string_translation;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('messenger'),
+      $container->get('string_translation')
+    );
+  }
+
+  /**
    * {@inheritdoc}
    */
   public function getQuestion() {
@@ -43,7 +76,7 @@ class HelpLockForm extends EntityConfirmFormBase {
     $ops_link = $this->entity->toLink($this->t('View'), 'canonical')->toString();
     $args = ['@link' => $link];
     $message = $this->t('The help topic @link has been locked.', $args);
-    drupal_set_message($message);
+    $this->messenger->addMessage($message);
     $this->getLogger('config_help')->notice('The help topic @link has been locked.', $args + [
       'link' => $ops_link,
     ]);
diff --git a/src/Form/HelpTopicForm.php b/src/Form/HelpTopicForm.php
index 4adcdac..b34f8ec 100644
--- a/src/Form/HelpTopicForm.php
+++ b/src/Form/HelpTopicForm.php
@@ -11,6 +11,8 @@ use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Extension\ThemeHandlerInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Language\LanguageInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -47,6 +49,13 @@ class HelpTopicForm extends EntityForm {
   protected $themeHandler;
 
   /**
+   * The Messenger service.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
    * Constructs a new help topic form.
    *
    * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
@@ -55,12 +64,18 @@ class HelpTopicForm extends EntityForm {
    *   The module handler.
    * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
    *   The theme handler.
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   The messenger service.
+   * @param TranslationInterface $string_translation
+   *   The translation manager.
    */
-  public function __construct(EntityTypeManagerInterface $entity_type_manager, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
+  public function __construct(EntityTypeManagerInterface $entity_type_manager, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler, MessengerInterface $messenger, TranslationInterface $string_translation) {
     $this->helpStorage = $entity_type_manager->getStorage('help_topic');
     $this->helpViewBuilder = $entity_type_manager->getViewBuilder('help_topic');
     $this->moduleHandler = $module_handler;
     $this->themeHandler = $theme_handler;
+    $this->messenger = $messenger;
+    $this->stringTranslation = $string_translation;
   }
 
   /**
@@ -70,7 +85,9 @@ class HelpTopicForm extends EntityForm {
     return new static(
       $container->get('entity_type.manager'),
       $container->get('module_handler'),
-      $container->get('theme_handler')
+      $container->get('theme_handler'),
+      $container->get('messenger'),
+      $container->get('string_translation')
     );
   }
 
@@ -333,14 +350,14 @@ class HelpTopicForm extends EntityForm {
     $args = ['@link' => $link];
     if ($status == SAVED_UPDATED) {
       $message = $this->t('The help topic @link has been updated.', $args);
-      drupal_set_message($message);
+      $this->messenger->addMessage($message);
       $this->getLogger('config_help')->notice('The help topic @link has been updated.', $args + [
         'link' => $ops_link,
       ]);
     }
     else {
       $message = $this->t('The help topic @link has been added.', $args);
-      drupal_set_message($message);
+      $this->messenger->addMessage($message);
       $this->getLogger('config_help')->notice('The help topic @link has been added.', $args + [
         'link' => $ops_link,
       ]);
diff --git a/src/Form/HelpUnlockForm.php b/src/Form/HelpUnlockForm.php
index 208e1cd..8ca02fa 100644
--- a/src/Form/HelpUnlockForm.php
+++ b/src/Form/HelpUnlockForm.php
@@ -4,7 +4,10 @@ namespace Drupal\config_help\Form;
 
 use Drupal\Core\Entity\EntityConfirmFormBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\Core\StringTranslation\TranslationInterface;
 use Drupal\Core\Url;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Provides a form for confirming unlocking of a help topic.
@@ -12,6 +15,36 @@ use Drupal\Core\Url;
 class HelpUnlockForm extends EntityConfirmFormBase {
 
   /**
+   * The Messenger service.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Constructs the help topic unlock form.
+   *
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   The messenger service.
+   * @param TranslationInterface $string_translation
+   *   The translation manager.
+   */
+  public function __construct(MessengerInterface $messenger, TranslationInterface $string_translation) {
+    $this->messenger = $messenger;
+    $this->stringTranslation = $string_translation;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('messenger'),
+      $container->get('string_translation')
+    );
+  }
+
+  /**
    * {@inheritdoc}
    */
   public function getQuestion() {
@@ -43,7 +76,7 @@ class HelpUnlockForm extends EntityConfirmFormBase {
     $ops_link = $this->entity->toLink($this->t('View'), 'canonical')->toString();
     $args = ['@link' => $link];
     $message = $this->t('The help topic @link has been unlocked.', $args);
-    drupal_set_message($message);
+    $this->messenger->addMessage($message);
     $this->getLogger('config_help')->notice('The help topic @link has been unlocked.', $args + [
       'link' => $ops_link,
     ]);