diff --git a/api/js/jsapi/jsapi.js b/api/js/jsapi/jsapi.js
index 90802d0391..4bcf6f40d4 100644
--- a/api/js/jsapi/jsapi.js
+++ b/api/js/jsapi/jsapi.js
@@ -830,4 +830,11 @@ jQuery(function(){
 
 jQuery(document).ready(function() {
 	jQuery('head').append('<link rel="manifest" href="/egroupware/pixelegg/manifest.json">');
-})
\ No newline at end of file
+})
+
+// IE does not support ES6 therefore we need to use polyfill function
+Number.isInteger = Number.isInteger || function(value) {
+  return typeof value === 'number' &&
+    isFinite(value) &&
+    Math.floor(value) === value;
+};
\ No newline at end of file