diff --git a/tests/Unit/EnvelopeTest.php b/tests/Unit/EnvelopeTest.php
index af412125..d7e4650e 100644
--- a/tests/Unit/EnvelopeTest.php
+++ b/tests/Unit/EnvelopeTest.php
@@ -24,24 +24,27 @@ public function testEnvelopeStack(): void
         $this->assertEquals([
             IdEnvelope::class,
         ], $stack);
+
+        $this->assertEquals('test-id', $message->getMetadata()[IdEnvelope::MESSAGE_ID_KEY]);
     }
 
     public function testEnvelopeDuplicates(): void
     {
         $message = new Message('handler', 'test');
-        $message = new IdEnvelope($message, 'test-id');
-        $message = new IdEnvelope($message, 'test-id');
-        $message = new IdEnvelope($message, 'test-id');
+        $message = new IdEnvelope($message, 'test-id-1');
+        $message = new IdEnvelope($message, 'test-id-2');
+        $message = new IdEnvelope($message, 'test-id-3');
 
         $this->assertEquals('test', $message->getMessage()->getData());
 
         $stack = $message->getMetadata()[EnvelopeInterface::ENVELOPE_STACK_KEY];
         $this->assertIsArray($stack);
-
         $this->assertEquals([
             IdEnvelope::class,
             IdEnvelope::class,
             IdEnvelope::class,
         ], $stack);
+
+        $this->assertEquals('test-id-3', $message->getMetadata()[IdEnvelope::MESSAGE_ID_KEY]);
     }
 }