diff --git a/mobile/android/chrome/content/browser.js b/mobile/android/chrome/content/browser.js
index da324dcb39b..c0041f53ab7 100644
--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -3738,11 +3738,9 @@ var ViewportHandler = {
     let allowZoomStr = windowUtils.getDocumentMetadata("viewport-user-scalable");
     let allowZoom = !/^(0|no|false)$/.test(allowZoomStr); // WebKit allows 0, "no", or "false"
 
-
-    if (scale == NaN && minScale == NaN && maxScale == NaN && allowZoomStr == "" && widthStr == "" && heightStr == "") {
+    if (isNaN(scale) && isNaN(minScale) && isNaN(maxScale) && allowZoomStr == "" && widthStr == "" && heightStr == "") {
       // Only check for HandheldFriendly if we don't have a viewport meta tag
       let handheldFriendly = windowUtils.getDocumentMetadata("HandheldFriendly");
-
       if (handheldFriendly == "true")
         return { defaultZoom: 1, autoSize: true, allowZoom: true, autoScale: true };