diff --git a/framework/core/src/Api/ApiServiceProvider.php b/framework/core/src/Api/ApiServiceProvider.php
index 83b74f1ce..aa2e53eae 100644
--- a/framework/core/src/Api/ApiServiceProvider.php
+++ b/framework/core/src/Api/ApiServiceProvider.php
@@ -75,6 +75,12 @@ class ApiServiceProvider extends AbstractServiceProvider
 
             return $pipe;
         });
+
+        $this->app->singleton('flarum.api.notification_serializers', function () {
+            return [
+                'discussionRenamed' => BasicDiscussionSerializer::class
+            ];
+        });
     }
 
     /**
@@ -82,7 +88,7 @@ class ApiServiceProvider extends AbstractServiceProvider
      */
     public function boot()
     {
-        $this->registerNotificationSerializers();
+        $this->setNotificationSerializers();
 
         AbstractSerializeController::setContainer($this->app);
         AbstractSerializeController::setEventDispatcher($events = $this->app->make('events'));
@@ -94,13 +100,12 @@ class ApiServiceProvider extends AbstractServiceProvider
     /**
      * Register notification serializers.
      */
-    protected function registerNotificationSerializers()
+    protected function setNotificationSerializers()
     {
         $blueprints = [];
-        $serializers = [
-            'discussionRenamed' => BasicDiscussionSerializer::class
-        ];
+        $serializers = $this->app->make('flarum.api.notification_serializers');
 
+        // Deprecated in beta 15, remove in beta 16
         $this->app->make('events')->dispatch(
             new ConfigureNotificationTypes($blueprints, $serializers)
         );
diff --git a/framework/core/src/Event/ConfigureNotificationTypes.php b/framework/core/src/Event/ConfigureNotificationTypes.php
index bca7296ac..89185b916 100644
--- a/framework/core/src/Event/ConfigureNotificationTypes.php
+++ b/framework/core/src/Event/ConfigureNotificationTypes.php
@@ -13,6 +13,9 @@ use Flarum\Notification\Blueprint\BlueprintInterface;
 use InvalidArgumentException;
 use ReflectionClass;
 
+/**
+ * @deprecated in beta 15, removed in beta 16
+ */
 class ConfigureNotificationTypes
 {
     /**
diff --git a/framework/core/src/Extend/Notification.php b/framework/core/src/Extend/Notification.php
new file mode 100644
index 000000000..ad91e18bb
--- /dev/null
+++ b/framework/core/src/Extend/Notification.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Extend;
+
+use Flarum\Extension\Extension;
+use Illuminate\Contracts\Container\Container;
+
+class Notification implements ExtenderInterface
+{
+    private $blueprints = [];
+    private $serializers = [];
+
+    public function type(string $blueprint, string $serializer, array $channelsEnabledByDefault = [])
+    {
+        $this->blueprints[$blueprint] = $channelsEnabledByDefault;
+        $this->serializers[$blueprint::getType()] = $serializer;
+
+        return $this;
+    }
+
+    public function extend(Container $container, Extension $extension = null)
+    {
+        $container->extend('flarum.notification.blueprints', function ($existingBlueprints) {
+            return array_merge($existingBlueprints, $this->blueprints);
+        });
+
+        $container->extend('flarum.api.notification_serializers', function ($existingSerializers) {
+            return array_merge($existingSerializers, $this->serializers);
+        });
+    }
+}
diff --git a/framework/core/src/Notification/NotificationServiceProvider.php b/framework/core/src/Notification/NotificationServiceProvider.php
index 3715cb3a5..c7cca3217 100644
--- a/framework/core/src/Notification/NotificationServiceProvider.php
+++ b/framework/core/src/Notification/NotificationServiceProvider.php
@@ -17,46 +17,62 @@ use ReflectionClass;
 
 class NotificationServiceProvider extends AbstractServiceProvider
 {
+    /**
+     * {@inheritdoc}
+     */
+    public function register()
+    {
+        $this->app->singleton('flarum.notification.blueprints', function () {
+            return [
+                DiscussionRenamedBlueprint::class => ['alert']
+            ];
+        });
+    }
+
     /**
      * {@inheritdoc}
      */
     public function boot()
     {
-        $this->registerNotificationTypes();
+        $this->setNotificationTypes();
     }
 
     /**
      * Register notification types.
      */
-    public function registerNotificationTypes()
+    protected function setNotificationTypes()
     {
-        $blueprints = [
-            DiscussionRenamedBlueprint::class => ['alert']
-        ];
+        $blueprints = $this->app->make('flarum.notification.blueprints');
 
+        // Deprecated in beta 15, remove in beta 16
         $this->app->make('events')->dispatch(
             new ConfigureNotificationTypes($blueprints)
         );
 
-        foreach ($blueprints as $blueprint => $enabled) {
-            Notification::setSubjectModel(
-                $type = $blueprint::getType(),
-                $blueprint::getSubjectModel()
-            );
+        foreach ($blueprints as $blueprint => $channelsEnabledByDefault) {
+            $this->addType($blueprint, $channelsEnabledByDefault);
+        }
+    }
 
+    protected function addType(string $blueprint, array $channelsEnabledByDefault)
+    {
+        Notification::setSubjectModel(
+            $type = $blueprint::getType(),
+            $blueprint::getSubjectModel()
+        );
+
+        User::addPreference(
+            User::getNotificationPreferenceKey($type, 'alert'),
+            'boolval',
+            in_array('alert', $channelsEnabledByDefault)
+        );
+
+        if ((new ReflectionClass($blueprint))->implementsInterface(MailableInterface::class)) {
             User::addPreference(
-                User::getNotificationPreferenceKey($type, 'alert'),
+                User::getNotificationPreferenceKey($type, 'email'),
                 'boolval',
-                in_array('alert', $enabled)
+                in_array('email', $channelsEnabledByDefault)
             );
-
-            if ((new ReflectionClass($blueprint))->implementsInterface(MailableInterface::class)) {
-                User::addPreference(
-                    User::getNotificationPreferenceKey($type, 'email'),
-                    'boolval',
-                    in_array('email', $enabled)
-                );
-            }
         }
     }
 }
diff --git a/framework/core/tests/integration/extenders/NotificationTest.php b/framework/core/tests/integration/extenders/NotificationTest.php
new file mode 100644
index 000000000..03388e529
--- /dev/null
+++ b/framework/core/tests/integration/extenders/NotificationTest.php
@@ -0,0 +1,68 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\Tests\integration\extenders;
+
+use Flarum\Extend;
+use Flarum\Notification\Blueprint\BlueprintInterface;
+use Flarum\Notification\Notification;
+
+class NotificationTest extends \Flarum\Tests\integration\TestCase
+{
+    /**
+     * @test
+     */
+    public function notification_type_doesnt_exist_by_default()
+    {
+        $this->assertArrayNotHasKey('customNotificationType', Notification::getSubjectModels());
+    }
+
+    /**
+     * @test
+     */
+    public function notification_type_exists_if_added()
+    {
+        $this->extend((new Extend\Notification)->type(
+            CustomNotificationType::class,
+            'customNotificationTypeSerializer'
+        ));
+
+        $this->app();
+
+        $this->assertArrayHasKey('customNotificationType', Notification::getSubjectModels());
+    }
+}
+
+class CustomNotificationType implements BlueprintInterface
+{
+    public function getFromUser()
+    {
+        // ...
+    }
+
+    public function getSubject()
+    {
+        // ...
+    }
+
+    public function getData()
+    {
+        // ...
+    }
+
+    public static function getType()
+    {
+        return 'customNotificationType';
+    }
+
+    public static function getSubjectModel()
+    {
+        return 'customNotificationTypeSubjectModel';
+    }
+}