diff --git a/wp-includes/customize/class-wp-customize-color-control.php b/wp-includes/customize/class-wp-customize-color-control.php
index 1e7ed17786..8d9827351a 100644
--- a/wp-includes/customize/class-wp-customize-color-control.php
+++ b/wp-includes/customize/class-wp-customize-color-control.php
@@ -91,8 +91,7 @@ class WP_Customize_Color_Control extends WP_Customize_Control {
 		?>
 		<# var defaultValue = '#RRGGBB', defaultValueAttr = '',
 			isHueSlider = data.mode === 'hue';
-
-		if ( data.defaultValue && ! isHueSlider ) {
+		if ( data.defaultValue && _.isString( data.defaultValue ) && ! isHueSlider ) {
 			if ( '#' !== data.defaultValue.substring( 0, 1 ) ) {
 				defaultValue = '#' + data.defaultValue;
 			} else {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e0f4a38c27..daab568fb4 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41255';
+$wp_version = '4.9-alpha-41256';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.