diff --git a/src/Symfony/Component/Messenger/Tests/TraceableMessageBusTest.php b/src/Symfony/Component/Messenger/Tests/TraceableMessageBusTest.php
index 1b03e0036b658..b87fffa82f339 100644
--- a/src/Symfony/Component/Messenger/Tests/TraceableMessageBusTest.php
+++ b/src/Symfony/Component/Messenger/Tests/TraceableMessageBusTest.php
@@ -37,7 +37,7 @@ public function testItTracesDispatch()
         unset($actualTracedMessage['callTime']); // don't check, too variable
         $this->assertEquals([
             'message' => $message,
-            'stamps' => [[$stamp]],
+            'stamps' => [$stamp],
             'caller' => [
                 'name' => 'TraceableMessageBusTest.php',
                 'file' => __FILE__,