diff --git a/dashboard-ui/thirdparty/jquery.unveil-custom.js b/dashboard-ui/thirdparty/jquery.unveil-custom.js
index 7083bbc462..03e114e8f7 100644
--- a/dashboard-ui/thirdparty/jquery.unveil-custom.js
+++ b/dashboard-ui/thirdparty/jquery.unveil-custom.js
@@ -21,15 +21,12 @@
     *       only accounts for vertical position, not horizontal.
     */
 
-    var thresholdX = Math.max(screen.availWidth);
-    var thresholdY = Math.max(screen.availHeight);
+    var thresholdX = screen.availWidth || 0;
+    var thresholdY = screen.availHeight || 0;
     var wheelEvent = (document.implementation.hasFeature('Event.wheel', '3.0') ? 'wheel' : 'mousewheel');
 
     function visibleInViewport(elem, partial) {
 
-        thresholdX = thresholdX || 0;
-        thresholdY = thresholdY || 0;
-
         var vpWidth = window.innerWidth,
             vpHeight = window.innerHeight;