diff --git a/lib/passport-cas.js b/lib/passport-cas.js
index 52f1c33..540c34d 100644
--- a/lib/passport-cas.js
+++ b/lib/passport-cas.js
@@ -168,7 +168,8 @@ CasStrategy.prototype.authenticate = function(req, options) {
 
   if (!ticket) {
     // Redirect to CAS server for authentication
-    self.redirect(self.casBaseUrl + '/login?service=' + encodeURIComponent(service), 307);
+    var date = new Date(Date.now());
+    self.redirect(`${self.casBaseUrl}/login?service=${encodeURIComponent(`${service}/?_cas_retry=${Math.round(date.getTime() / 60000)}`)}`, 307);
   }
   else {
     // User has returned from CAS site with a ticket
@@ -176,7 +177,7 @@ CasStrategy.prototype.authenticate = function(req, options) {
 
       // Ticket validation failed
       if (err) {
-        var date = new Date();
+        var date = new Date(Date.now());
         var token = Math.round(date.getTime() / 60000);
         if (req.query['_cas_retry'] != token) {
             // There was a CAS error. A common cause is when an old