diff --git src/wp-admin/customize.php src/wp-admin/customize.php
index aa949e5..9cfb278 100644
--- src/wp-admin/customize.php
+++ src/wp-admin/customize.php
@@ -132,7 +132,7 @@ do_action( 'customize_controls_print_scripts' );
' . get_bloginfo( 'name' ) . '' );
+ echo sprintf( __( 'You are customizing %s' ), '' . ( get_bloginfo( 'name' ) ? get_bloginfo( 'name' ) : __( '(untitled)' ) ) . '' );
?>
diff --git src/wp-admin/js/customize-controls.js src/wp-admin/js/customize-controls.js
index e78d2c9..e3fdf16 100644
--- src/wp-admin/js/customize-controls.js
+++ src/wp-admin/js/customize-controls.js
@@ -3605,7 +3605,7 @@
// Bind site title display to the corresponding field.
if ( title.length ) {
$( '#customize-control-blogname input' ).on( 'input', function() {
- title.text( this.value );
+ title.text( this.value || api.l10n.untitledBlogName );
} );
}
diff --git src/wp-includes/script-loader.php src/wp-includes/script-loader.php
index 2ac34ed..7dfb15a 100644
--- src/wp-includes/script-loader.php
+++ src/wp-includes/script-loader.php
@@ -443,6 +443,7 @@ function wp_default_scripts( &$scripts ) {
'loginIframeTitle' => __( 'Session expired' ),
'collapseSidebar' => __( 'Collapse Sidebar' ),
'expandSidebar' => __( 'Expand Sidebar' ),
+ 'untitledBlogName' => __( '(untitled)' ),
// Used for overriding the file types allowed in plupload.
'allowedFiles' => __( 'Allowed Files' ),
) );