diff --git a/src/Contracts/MailProviderContract.php b/src/Contracts/MailProviderContract.php
index f592264..f769434 100644
--- a/src/Contracts/MailProviderContract.php
+++ b/src/Contracts/MailProviderContract.php
@@ -4,5 +4,5 @@
 
 interface MailProviderContract
 {
-    public function driver(?string $driver = null);
+    public function driver(string $driver = null);
 }
diff --git a/tests/TestCase.php b/tests/TestCase.php
index ec47660..f123de7 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -36,16 +36,16 @@ public function getEnvironmentSetUp($app)
             'prefix' => '',
         ]);
 
-        $migration = include __DIR__.'/../database/migrations/create_mailables_table.php.stub';
+        $migration = include __DIR__.'/../database/migrations/1_create_mails_table.php.stub';
         $migration->up();
 
-        $migration = include __DIR__.'/../database/migrations/create_mail_attachments_table.php.stub';
+        $migration = include __DIR__.'/../database/migrations/2_create_mail_attachments_table.php.stub';
         $migration->up();
 
-        $migration = include __DIR__.'/../database/migrations/create_mail_events_table.php.stub';
+        $migration = include __DIR__.'/../database/migrations/2_create_mail_events_table.php.stub';
         $migration->up();
 
-        $migration = include __DIR__.'/../database/migrations/create_mails_table.php.stub';
+        $migration = include __DIR__.'/../database/migrations/2_create_mailables_table.php.stub';
         $migration->up();
     }
 }