diff --git a/easywks/types.py b/easywks/types.py
index ba76162..bffdaf9 100644
--- a/easywks/types.py
+++ b/easywks/types.py
@@ -218,6 +218,7 @@ Encrypt live everybody is.
         encrypted |= pgp_sign(self.domain, encrypted)
         payload = MIMEApplication(str(encrypted), _subtype='octet-stream')
         mpenc = MIMEApplication(payload.as_string(policy=default), _subtype='pgp-encrypted')
+        mpenc['Version'] = '1'
         email = MIMEMultipart(_subtype='encrypted', _subparts=[mpenc], policy=default,
                               protocol='application/pgp-encrypted')
         email['Subject'] = 'Your key has been published'