diff --git a/test/Media_RSS_Item_SerializationTest.php b/test/Media_RSS_Item_SerializationTest.php
index 9f0d91e..2c83b12 100644
--- a/test/Media_RSS_Item_SerializationTest.php
+++ b/test/Media_RSS_Item_SerializationTest.php
@@ -28,8 +28,45 @@ public function test_serialize_and_deserialize_yield_the_same_thing()
         $this->assertEquals('b', $item2->getB());
     }
 
+    public function test_unserialize_rejects_invalid_serialization_version()
+    {
+        $item = new Media_RSS_Item('example.mp3');
+        $item->setA('a');
+        $item->setB('b');
+
+        $serialized = serialize($item);
+        $serialized = preg_replace('/:"serialVersion";i:\d+;/', ':"serialVersion";i:0;', $serialized);
+        $this->expectException(SerializationException::class);
+        $item2 = unserialize($serialized);
+    }
+
+    public function test_unserialize_does_not_overwrite_properties_set_from_fs_metadata()
+    {
+        $item = new Media_RSS_Item('example.mp3');
+        $item->setA('a');
+        $item->setB('b');
+
+        $serialized = $item->serialize($item);
+
+        file_put_contents('example2.abc', 'abcde');
+        $filemtime = time()-100;
+        touch('example2.abc', $filemtime);
+        $item2 = new Media_RSS_Item('example2.abc');
+        $item2->unserialize($serialized);
+
+        $this->assertEquals('a', $item2->getA());
+        $this->assertEquals('b', $item2->getB());
+
+        $this->assertEquals(5, $item2->getLength());
+        $this->assertEquals(date('r', $filemtime), $item2->getPubDate());
+        $this->assertEquals('example2.abc', $item2->getFilename());
+        $this->assertEquals('abc', $item2->getExtension());
+        $this->assertEquals('http://www.example.com/mp3/example2.abc', $item2->getLink());
+    }
+
     public function tearDown(): void
     {
         unlink('example.mp3');
+        file_exists('example2.abc') && unlink('example2.abc');
     }
 }