diff --git a/src/wp-includes/js/customize-base.js b/src/wp-includes/js/customize-base.js
index 765c59505d..d2488ddc10 100644
--- a/src/wp-includes/js/customize-base.js
+++ b/src/wp-includes/js/customize-base.js
@@ -184,7 +184,7 @@ window.wp = window.wp || {};
 			to = this.validate( to );
 
 			// Bail if the sanitized value is null or unchanged.
-			if ( null === to || this._value === to )
+			if ( null === to || _.isEqual( from, to ) )
 				return this;
 
 			this._value = to;
diff --git a/src/wp-includes/script-loader.php b/src/wp-includes/script-loader.php
index 2cc0870788..154393fbc1 100644
--- a/src/wp-includes/script-loader.php
+++ b/src/wp-includes/script-loader.php
@@ -377,7 +377,7 @@ function wp_default_scripts( &$scripts ) {
 
 	$scripts->add( 'hoverIntent', "/wp-includes/js/hoverIntent$suffix.js", array('jquery'), 'r7', 1 );
 
-	$scripts->add( 'customize-base',     "/wp-includes/js/customize-base$suffix.js",     array( 'jquery', 'json2' ), false, 1 );
+	$scripts->add( 'customize-base',     "/wp-includes/js/customize-base$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 );
 	$scripts->add( 'customize-models',   "/wp-includes/js/customize-models.js", array( 'underscore', 'backbone' ), false, 1 );