diff --git a/src/Symfony/Component/Mime/Part/TextPart.php b/src/Symfony/Component/Mime/Part/TextPart.php
index 549a5fe1e02fe..bddca0a2b474f 100644
--- a/src/Symfony/Component/Mime/Part/TextPart.php
+++ b/src/Symfony/Component/Mime/Part/TextPart.php
@@ -218,7 +218,7 @@ private function chooseEncoding(): string
     public function __sleep(): array
     {
         // convert resources to strings for serialization
-        if (null !== $this->seekable) {
+        if (null !== $this->seekable || $this->body instanceof File) {
             $this->body = $this->getBody();
             $this->seekable = null;
         }
diff --git a/src/Symfony/Component/Mime/Tests/EmailTest.php b/src/Symfony/Component/Mime/Tests/EmailTest.php
index f5ffbb7638429..8dba651ffb882 100644
--- a/src/Symfony/Component/Mime/Tests/EmailTest.php
+++ b/src/Symfony/Component/Mime/Tests/EmailTest.php
@@ -483,6 +483,7 @@ public function testSerialize()
         $name = __DIR__.'/Fixtures/mimetypes/test';
         $file = fopen($name, 'r');
         $e->addPart(new DataPart($file, 'test'));
+        $e->attachFromPath($name, 'same_test');
         $expected = clone $e;
         $n = unserialize(serialize($e));
         $this->assertEquals($expected->getHeaders(), $n->getHeaders());