diff --git a/lib/experimental/site-editor-permalinks.php b/lib/experimental/site-editor-permalinks.php
index 1f73043f96488f..7cd8841927e729 100644
--- a/lib/experimental/site-editor-permalinks.php
+++ b/lib/experimental/site-editor-permalinks.php
@@ -39,7 +39,7 @@ function gutenberg_get_posts_dataviews_url( $path = '', $query = array() ) {
 
 function gutenberg_redirect_site_editor_to_design() {
 	global $pagenow;
-	if ( 'site-editor.php' !== $pagenow || isset( $_REQUEST['p'] ) || ! isset( $_SERVER['querystring'] ) ) {
+	if ( 'site-editor.php' !== $pagenow || isset( $_REQUEST['p'] ) || ! isset( $_SERVER['QUERY_STRING'] ) ) {
 		return;
 	}