diff --git a/lib/SwiftSignerCryptGPG.php b/lib/SwiftSignerCryptGPG.php
index 48e8f43..a236e5f 100644
--- a/lib/SwiftSignerCryptGPG.php
+++ b/lib/SwiftSignerCryptGPG.php
@@ -87,6 +87,7 @@ public function signMessage(Swift_Message $message)
         // Prepare message final form
         $message
             ->setEncoder($encoder)
+            ->setBody(null)
             ->setChildren([$pgpmime, $encryptedMessage]);
 
         $type = $message->getHeaders()->get('Content-Type');