diff --git a/addons/mail/wizard/mail_compose_message.py b/addons/mail/wizard/mail_compose_message.py
index 7e269ab7379..733057de1cf 100644
--- a/addons/mail/wizard/mail_compose_message.py
+++ b/addons/mail/wizard/mail_compose_message.py
@@ -234,7 +234,7 @@ class mail_compose_message(osv.TransientModel):
                 # mail.message values, according to the wizard options
                 post_values = {
                     'subject': wizard.subject,
-                    'body': wizard.body,
+                    'body': wizard.body or '',
                     'parent_id': wizard.parent_id and wizard.parent_id.id,
                     'partner_ids': [partner.id for partner in wizard.partner_ids],
                     'attachment_ids': [attach.id for attach in wizard.attachment_ids],