diff --git a/src/Symfony/Component/Mailer/Bridge/Mailomat/Tests/Transport/MailomatApiTransportTest.php b/src/Symfony/Component/Mailer/Bridge/Mailomat/Tests/Transport/MailomatApiTransportTest.php
index 488d9da132074..b75f3bd2b5b86 100644
--- a/src/Symfony/Component/Mailer/Bridge/Mailomat/Tests/Transport/MailomatApiTransportTest.php
+++ b/src/Symfony/Component/Mailer/Bridge/Mailomat/Tests/Transport/MailomatApiTransportTest.php
@@ -27,7 +27,7 @@ class MailomatApiTransportTest extends TestCase
     /**
      * @dataProvider getTransportData
      */
-    public function testToString(MailomatApiTransport $transport, string $expected): void
+    public function testToString(MailomatApiTransport $transport, string $expected)
     {
         $this->assertSame($expected, (string) $transport);
     }