diff --git a/src/database/mongo/main.js b/src/database/mongo/main.js
index 4ca3bb2cd3..9381fbbc39 100644
--- a/src/database/mongo/main.js
+++ b/src/database/mongo/main.js
@@ -92,6 +92,7 @@ module.exports = function (db, module) {
 	};
 
 	module.pexpireAt = function (key, timestamp, callback) {
+		timestamp = Math.min(timestamp, 8640000000000000);
 		module.setObjectField(key, 'expireAt', new Date(timestamp), callback);
 	};
 };
diff --git a/src/socket.io/user/ban.js b/src/socket.io/user/ban.js
index 191b98767e..3af03becb8 100644
--- a/src/socket.io/user/ban.js
+++ b/src/socket.io/user/ban.js
@@ -10,6 +10,7 @@ var privileges = require('../../privileges');
 var plugins = require('../../plugins');
 var emailer = require('../../emailer');
 var translator = require('../../translator');
+var utils = require('../../../public/src/utils');
 
 module.exports = function (SocketUser) {
 	SocketUser.banUsers = function (socket, data, callback) {
@@ -108,7 +109,7 @@ module.exports = function (SocketUser) {
 					subject: '[[email:banned.subject, ' + siteTitle + ']]',
 					site_title: siteTitle,
 					username: username,
-					until: until ? new Date(until).toString() : false,
+					until: until ? utils.toISOString(until) : false,
 					reason: reason,
 				};