diff --git a/addons/mail/static/src/js/attachment_box.js b/addons/mail/static/src/js/attachment_box.js
index cc5d53ee1c0..17e91b410e9 100644
--- a/addons/mail/static/src/js/attachment_box.js
+++ b/addons/mail/static/src/js/attachment_box.js
@@ -7,6 +7,7 @@ var Widget = require('web.Widget');
 var DocumentViewer = require('mail.DocumentViewer');
 
 var QWeb = core.qweb;
+var _t = core._t;
 
 var AttachmentBox = Widget.extend({
     template: 'mail.chatter.AttachmentBox',
@@ -36,7 +37,7 @@ var AttachmentBox = Widget.extend({
         _.each(attachments, function (attachment) {
             // required for compatibility with the chatter templates.
             attachment.url = '/web/content/' + attachment.id + '?download=true';
-            attachment.filename = attachment.name || 'unnamed';
+            attachment.filename = attachment.name || _t('unnamed');
         });
         var sortedAttachments = _.partition(attachments, function (att) {
             return att.mimetype && att.mimetype.split('/')[0] === 'image';
diff --git a/addons/mail/static/src/js/models/messages/abstract_message.js b/addons/mail/static/src/js/models/messages/abstract_message.js
index 6a7b02d6e94..ee9374996d4 100644
--- a/addons/mail/static/src/js/models/messages/abstract_message.js
+++ b/addons/mail/static/src/js/models/messages/abstract_message.js
@@ -48,6 +48,9 @@ var AbstractMessage =  Class.extend({
         this._type = data.message_type || undefined;
 
         this._processAttachmentURL();
+        this._attachmentIDs.forEach(function (attachment) {
+            attachment.filename = attachment.filename || attachment.name || _t("unnamed");
+        });
     },
 
     //--------------------------------------------------------------------------