diff --git a/src/Symfony/Component/Messenger/Envelope.php b/src/Symfony/Component/Messenger/Envelope.php
index 48743e79bd706..74ab6edcce2ff 100644
--- a/src/Symfony/Component/Messenger/Envelope.php
+++ b/src/Symfony/Component/Messenger/Envelope.php
@@ -95,7 +95,7 @@ public function withoutStampsOfType(string $type): self
 
     public function last(string $stampFqcn): ?StampInterface
     {
-        return isset($this->stamps[$stampFqcn = $stampFqcn]) ? end($this->stamps[$stampFqcn]) : null;
+        return isset($this->stamps[$stampFqcn]) ? end($this->stamps[$stampFqcn]) : null;
     }
 
     /**