diff --git a/tests/Assets/Notifications/CustomNotifiableStub.php b/tests/Assets/Notifications/CustomNotifiableStub.php
index b451c0a1..54885e56 100644
--- a/tests/Assets/Notifications/CustomNotifiableStub.php
+++ b/tests/Assets/Notifications/CustomNotifiableStub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace LaravelDoctrineTest\ORM\Assets\Notifications;
 
 use LaravelDoctrine\ORM\Notifications\Notifiable;
@@ -8,7 +10,7 @@ class CustomNotifiableStub
 {
     use Notifiable;
 
-    public function routeNotificationForDoctrine()
+    public function routeNotificationForDoctrine(): string
     {
         return 'custom';
     }
diff --git a/tests/Assets/Notifications/NotifiableStub.php b/tests/Assets/Notifications/NotifiableStub.php
index 49e8c0d4..fc28765a 100644
--- a/tests/Assets/Notifications/NotifiableStub.php
+++ b/tests/Assets/Notifications/NotifiableStub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace LaravelDoctrineTest\ORM\Assets\Notifications;
 
 use LaravelDoctrine\ORM\Notifications\Notifiable;
@@ -8,4 +10,3 @@ class NotifiableStub
 {
     use Notifiable;
 }
-
diff --git a/tests/Assets/Notifications/NotificationDatabaseStub.php b/tests/Assets/Notifications/NotificationDatabaseStub.php
index 579d3337..e7ca3c22 100644
--- a/tests/Assets/Notifications/NotificationDatabaseStub.php
+++ b/tests/Assets/Notifications/NotificationDatabaseStub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace LaravelDoctrineTest\ORM\Assets\Notifications;
 
 use Illuminate\Notifications\Notification as IlluminateNotification;
@@ -7,7 +9,7 @@
 
 class NotificationDatabaseStub extends IlluminateNotification
 {
-    public function toDatabase()
+    public function toDatabase(): Notification
     {
         return new Notification();
     }
diff --git a/tests/Assets/Notifications/NotificationInvalidStub.php b/tests/Assets/Notifications/NotificationInvalidStub.php
index 9efe61fa..8c69ddf6 100644
--- a/tests/Assets/Notifications/NotificationInvalidStub.php
+++ b/tests/Assets/Notifications/NotificationInvalidStub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace LaravelDoctrineTest\ORM\Assets\Notifications;
 
 use Illuminate\Notifications\Notification as IlluminateNotification;
diff --git a/tests/Assets/Notifications/NotificationStub.php b/tests/Assets/Notifications/NotificationStub.php
index df5529e6..07797275 100644
--- a/tests/Assets/Notifications/NotificationStub.php
+++ b/tests/Assets/Notifications/NotificationStub.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace LaravelDoctrineTest\ORM\Assets\Notifications;
 
 use Illuminate\Notifications\Notification as IlluminateNotification;
@@ -7,7 +9,7 @@
 
 class NotificationStub extends IlluminateNotification
 {
-    public function toEntity()
+    public function toEntity(): Notification
     {
         return new Notification();
     }