diff --git a/addons/portal/i18n/portal.pot b/addons/portal/i18n/portal.pot
index ed76b6fef14..200958639ca 100644
--- a/addons/portal/i18n/portal.pot
+++ b/addons/portal/i18n/portal.pot
@@ -19,7 +19,7 @@ msgstr ""
 #. openerp-web
 #: code:addons/portal/static/src/js/portal_sidebar.js:0
 #, python-format
-msgid "%d days overdue"
+msgid "%1d days overdue"
 msgstr ""
 
 #. module: portal
@@ -411,7 +411,7 @@ msgstr ""
 #. openerp-web
 #: code:addons/portal/static/src/js/portal_sidebar.js:0
 #, python-format
-msgid "Due in %d days"
+msgid "Due in %1d days"
 msgstr ""
 
 #. module: portal
diff --git a/addons/portal/static/src/js/portal_sidebar.js b/addons/portal/static/src/js/portal_sidebar.js
index b565e27868b..d081ddec68d 100644
--- a/addons/portal/static/src/js/portal_sidebar.js
+++ b/addons/portal/static/src/js/portal_sidebar.js
@@ -4,6 +4,7 @@ odoo.define('portal.PortalSidebar', function (require) {
 var core = require('web.core');
 var publicWidget = require('web.public.widget');
 var time = require('web.time');
+var session = require('web.session');
 
 var _t = core._t;
 
@@ -34,14 +35,18 @@ var PortalSidebar = publicWidget.Widget.extend({
                 diff = dateTime.diff(today, 'days', true),
                 displayStr;
 
-            if (diff === 0) {
-                displayStr = _t('Due today');
-            } else if (diff > 0) {
-                displayStr = _.str.sprintf(_t('Due in %d days'), Math.abs(diff));
-            } else {
-                displayStr = _.str.sprintf(_t('%d days overdue'), Math.abs(diff));
-            }
-             $(el).text(displayStr);
+            session.is_bound.then(function (){
+                if (diff === 0) {
+                    displayStr = _t('Due today');
+                } else if (diff > 0) {
+                    // Workaround: force uniqueness of these two translations. We use %1d because the string
+                    // with %d is already used in mail and mail's translations are not sent to the frontend.
+                    displayStr = _.str.sprintf(_t('Due in %1d days'), Math.abs(diff));
+                } else {
+                    displayStr = _.str.sprintf(_t('%1d days overdue'), Math.abs(diff));
+                }
+                $(el).text(displayStr);
+            });
         });
     },
     /**