diff --git a/lib/main.js b/lib/main.js
index 90dc0428..79af6ac3 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -172,6 +172,7 @@ SockJS.CONNECTING = 0;
 SockJS.OPEN = 1;
 SockJS.CLOSING = 2;
 SockJS.CLOSED = 3;
+SockJS.WATCHDOG_WEBSOCKET_TIMEOUT = 30000; // The heartbeat appears every 25 seconds, so we have 5 seconds delay buffer
 
 SockJS.prototype._receiveInfo = function(info, rtt) {
   debug('_receiveInfo', rtt);
@@ -241,6 +242,11 @@ SockJS.prototype._transportTimeout = function() {
   }
 };
 
+SockJS.prototype._websocketWatchdogCb = function(websocket) {
+  debug("watchdog websocket timeout");
+  websocket._close(1006, 'Server lost session');
+}
+
 SockJS.prototype._transportMessage = function(msg) {
   debug('_transportMessage', msg);
   var self = this
@@ -257,6 +263,8 @@ SockJS.prototype._transportMessage = function(msg) {
     case 'h':
       this.dispatchEvent(new Event('heartbeat'));
       debug('heartbeat', this.transport);
+      clearTimeout(this.heartbeatWatchdog);
+      this.heartbeatWatchdog = setTimeout(this._websocketWatchdogCb, SockJS.WATCHDOG_WEBSOCKET_TIMEOUT, this);
       return;
   }
 
@@ -321,6 +329,7 @@ SockJS.prototype._open = function() {
     this.transport = this._transport.transportName;
     this.dispatchEvent(new Event('open'));
     debug('connected', this.transport);
+    this.heartbeatWatchdog = setTimeout(this._websocketWatchdogCb, SockJS.WATCHDOG_WEBSOCKET_TIMEOUT, this);
   } else {
     // The server might have been restarted, and lost track of our
     // connection.