diff --git a/demos/mobile/html/index.html b/demos/mobile/html/index.html
index e527aa3b9..55906503d 100644
--- a/demos/mobile/html/index.html
+++ b/demos/mobile/html/index.html
@@ -2,7 +2,7 @@
 <!-- HTML file to host Blockly in a mobile WebView. -->
 <html>
 <head>
-  <!--<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">-->
+  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
   <style type="text/css">
     html, body, #blocklyDiv {
       border: 0;
