diff --git a/src/wp-admin/admin-header.php b/src/wp-admin/admin-header.php
index cbce31b59f..beeb97712a 100644
--- a/src/wp-admin/admin-header.php
+++ b/src/wp-admin/admin-header.php
@@ -205,7 +205,7 @@ $admin_body_class .= ' no-customize-support no-svg';
  */
 $admin_body_classes = apply_filters( 'admin_body_class', '' );
 ?>
-<body class="wp-admin wp-core-ui no-js <?php echo $admin_body_classes . ' ' . $admin_body_class; ?>">
+<body class="wp-admin wp-core-ui no-js <?php echo ltrim($admin_body_classes . ' ' . $admin_body_class; ?>">
 <script type="text/javascript">
 	document.body.className = document.body.className.replace('no-js','js');
 </script>
diff --git a/wp-activate.php b/wp-activate.php
new file mode 100644
index 0000000000..1a7d1ecdb9