diff --git a/lib/wechat.js b/lib/wechat.js
index bd253d87..770eb15d 100644
--- a/lib/wechat.js
+++ b/lib/wechat.js
@@ -340,6 +340,11 @@ var respond = function (handler) {
           req.wxsession = new Session(openid, req);
           req.wxsession.cookie = req.session.cookie;
         } else {
+          // add by xjmalm, convert string type to Date in case some of the session storage only stores the simple data types
+          if (session.cookie && 'string' === typeof session.cookie.expires) {
+            session.cookie.expires = new Date(session.cookie.expires);
+          }
+
           req.wxsession = new Session(openid, req, session);
         }
         done();