diff --git a/src/wp-includes/js/customize-preview.js b/src/wp-includes/js/customize-preview.js
index 44ba23b..c3bbcb7 100644
--- a/src/wp-includes/js/customize-preview.js
+++ b/src/wp-includes/js/customize-preview.js
@@ -64,6 +64,7 @@
 
 	$( function() {
 		api.settings = window._wpCustomizeSettings;
+		api.l10n = window._wpCustomizePreviewL10n;
 		if ( ! api.settings )
 			return;
 
@@ -118,7 +119,7 @@
 		// Display a loading indicator when preview is reloading
 		api.preview.bind( 'loading', function () {
 			$( 'body' ).addClass( 'customizer-navigating-away' );
-			$( 'html' ).prop( 'title', 'Loading...' );
+			$( 'html' ).prop( 'title', api.l10n.loading );
 		});
 
 		/* Custom Backgrounds */
diff --git a/src/wp-includes/script-loader.php b/src/wp-includes/script-loader.php
index 23c8905..cc0096f 100644
--- a/src/wp-includes/script-loader.php
+++ b/src/wp-includes/script-loader.php
@@ -382,6 +382,10 @@ function wp_default_scripts( &$scripts ) {
 	$scripts->add( 'customize-base',     "/wp-includes/js/customize-base$suffix.js",     array( 'jquery', 'json2', 'underscore' ), false, 1 );
 	$scripts->add( 'customize-loader',   "/wp-includes/js/customize-loader$suffix.js",   array( 'customize-base' ), false, 1 );
 	$scripts->add( 'customize-preview',  "/wp-includes/js/customize-preview$suffix.js",  array( 'customize-base' ), false, 1 );
+	did_action( 'init' ) && $scripts->localize( 'customize-preview', '_wpCustomizePreviewL10n', array(
+		'loading'  => __( 'Loading ...' ),
+	) );
+
 	$scripts->add( 'customize-models',   "/wp-includes/js/customize-models.js", array( 'underscore', 'backbone' ), false, 1 );
 	$scripts->add( 'customize-views',    "/wp-includes/js/customize-views.js",  array( 'jquery', 'underscore', 'imgareaselect', 'customize-models' ), false, 1 );
 	$scripts->add( 'customize-controls', "/wp-admin/js/customize-controls$suffix.js", array( 'customize-base' ), false, 1 );
-- 
2.2.2