diff --git a/kfet/static/kfet/js/kfet.js b/kfet/static/kfet/js/kfet.js
index b8a44244..bdf5b69b 100644
--- a/kfet/static/kfet/js/kfet.js
+++ b/kfet/static/kfet/js/kfet.js
@@ -33,12 +33,12 @@ $(document).ready(function() {
 
 class KfetWebsocket {
 
-    static get default_data() {
-        return {"relative_url": "", "default_msg": {}};
+    static get defaults() {
+        return {"relative_url": "", "default_msg": {}, "handlers": []};
     }
 
     constructor(data) {
-        $.extend(this, this.constructor.default_data, data);
+        $.extend(this, this.constructor.defaults, data);
     }
     
     get url() {
@@ -49,13 +49,22 @@ class KfetWebsocket {
         return websocket_protocol+"://" + location_url + this.relative_url ;
     }
 
-    listen(handle_func) {
+    add_handler(handler) {
+        if (!this.socket)
+            this.listen();
+
+        this.handlers.push(handler);
+    }
+
+    listen() {
         var that = this;
         this.socket = new ReconnectingWebSocket(this.url);
 
         this.socket.onmessage = function(e) {
             var data = $.extend({}, that.default_msg, JSON.parse(e.data));
-            handle_func(data);
+            for (let handler of that.handlers) {
+                handler(data);
+            }
         }
     }
 }
diff --git a/kfet/templates/kfet/kpsul.html b/kfet/templates/kfet/kpsul.html
index cf558647..4ac1354c 100644
--- a/kfet/templates/kfet/kpsul.html
+++ b/kfet/templates/kfet/kpsul.html
@@ -1320,7 +1320,7 @@ $(document).ready(function() {
     // Synchronization
     // -----
 
-    OperationWebSocket.listen(function(data) {
+    OperationWebSocket.add_handler(function(data) {
         for (var i=0; i<data['opegroups'].length; i++) {
             if (data['opegroups'][i]['add']) {
                 khistory.addOpeGroup(data['opegroups'][i]);