diff --git a/src/Symfony/Component/Messenger/Transport/Serialization/PhpSerializer.php b/src/Symfony/Component/Messenger/Transport/Serialization/PhpSerializer.php
index 659c0e5424..3a4804903c 100644
--- a/src/Symfony/Component/Messenger/Transport/Serialization/PhpSerializer.php
+++ b/src/Symfony/Component/Messenger/Transport/Serialization/PhpSerializer.php
@@ -29,7 +29,7 @@ class PhpSerializer implements SerializerInterface
             throw new MessageDecodingFailedException('Encoded envelope should have at least a "body".');
         }
 
-        if (str_ends_with($encodedEnvelope['body'], '}')) {
+        if (!str_ends_with($encodedEnvelope['body'], '}')) {
             $encodedEnvelope['body'] = base64_decode($encodedEnvelope['body']);
         }