diff --git a/js/gui.js b/js/gui.js
index a67d5f37b7..b6e0817454 100644
--- a/js/gui.js
+++ b/js/gui.js
@@ -1,8 +1,15 @@
 var GUI_control = function() {
     this.active_tab;
-    
+    this.operating_system;
     this.interval_array = [];
     this.timeout_array = [];
+    
+    // check which operating system is user running
+    if (navigator.appVersion.indexOf("Win") != -1)          this.operating_system = "Windows";
+    else if (navigator.appVersion.indexOf("Mac") != -1)     this.operating_system = "MacOS";
+    else if (navigator.appVersion.indexOf("CrOS") != -1)    this.operating_system = "ChromeOS";
+    else if (navigator.appVersion.indexOf("Linux") != -1)   this.operating_system = "Linux";
+    else if (navigator.appVersion.indexOf("X11") != -1)     this.operating_system = "UNIX";
 };
 
 // Timer managing methods