diff --git a/src/app/root-view.coffee b/src/app/root-view.coffee
index 558143889..4ef9662b8 100644
--- a/src/app/root-view.coffee
+++ b/src/app/root-view.coffee
@@ -34,6 +34,7 @@ class RootView extends View
   title: null
 
   initialize: ->
+    @addClass('dev-mode') if atom.devMode
     @command 'toggle-dev-tools', => atom.toggleDevTools()
     @on 'focus', (e) => @handleFocus(e)
     @subscribe $(window), 'focus', (e) =>
diff --git a/static/atom.css b/static/atom.css
index 187f53b74..f029ddc77 100644
--- a/static/atom.css
+++ b/static/atom.css
@@ -10,7 +10,7 @@ html, body {
   position: relative;
 }
 
-.is-dev-mode #root-view:before {
+#root-view.dev-mode:before {
   content: "";
   height: 3px;
   display: block;
diff --git a/static/index.html b/static/index.html
index a78a5a823..0e27bf115 100644
--- a/static/index.html
+++ b/static/index.html
@@ -23,12 +23,6 @@
         console.error(error.stack || error);
       }
     }
-
-    document.addEventListener('DOMContentLoaded', function() {
-      if (window.location.params.devMode) {
-        document.body.setAttribute('class', 'is-dev-mode')
-      }
-    })
   </script>
 
   <script src='../src/stdlib/require.js'></script>