diff --git a/tests/MailboxRouteTest.php b/tests/MailboxRouteTest.php
index 7e1de29..594b793 100644
--- a/tests/MailboxRouteTest.php
+++ b/tests/MailboxRouteTest.php
@@ -8,7 +8,7 @@
 
 class MailboxRouteTest extends TestCase
 {
-    public function emailDataProvider()
+    public static function emailDataProvider()
     {
         return [
             ['hello@beyondco.de', 'hello@beyondco.de', 'wrong@beyondco.de'],
@@ -125,7 +125,7 @@ public function it_matches_requirements()
         $this->assertTrue($route->matches($message));
     }
 
-    public function subjectDataProvider()
+    public static function subjectDataProvider()
     {
         return [
             ['New Laravel Packages', 'New Laravel Packages', 'Old Laravel Packages'],