diff --git a/src/wp-admin/includes/class-custom-background.php b/src/wp-admin/includes/class-custom-background.php
index 2eb3ccfd64..1d1cce73b8 100644
--- a/src/wp-admin/includes/class-custom-background.php
+++ b/src/wp-admin/includes/class-custom-background.php
@@ -42,8 +42,11 @@ class Custom_Background {
 	 * Constructor - Registers administration header callback.
 	 *
 	 * @since 3.0.0
-	 * @param callable $admin_header_callback
-	 * @param callable $admin_image_div_callback Optional custom image div output callback.
+	 *
+	 * @param callable $admin_header_callback    Optional. Administration header callback.
+	 *                                           Default empty string.
+	 * @param callable $admin_image_div_callback Optional. Custom image div output callback.
+	 *                                           Default empty string.
 	 */
 	public function __construct( $admin_header_callback = '', $admin_image_div_callback = '' ) {
 		$this->admin_header_callback    = $admin_header_callback;
diff --git a/src/wp-admin/includes/class-custom-image-header.php b/src/wp-admin/includes/class-custom-image-header.php
index ee3bcb12ec..a4b04bf3fc 100644
--- a/src/wp-admin/includes/class-custom-image-header.php
+++ b/src/wp-admin/includes/class-custom-image-header.php
@@ -47,11 +47,13 @@ class Custom_Image_Header {
 	private $updated;
 
 	/**
-	 * Constructor - Register administration header callback.
+	 * Constructor - Registers administration header callback.
 	 *
 	 * @since 2.1.0
-	 * @param callable $admin_header_callback
-	 * @param callable $admin_image_div_callback Optional custom image div output callback.
+	 *
+	 * @param callable $admin_header_callback    Administration header callback.
+	 * @param callable $admin_image_div_callback Optional. Custom image div output callback.
+	 *                                           Default empty string.
 	 */
 	public function __construct( $admin_header_callback, $admin_image_div_callback = '' ) {
 		$this->admin_header_callback    = $admin_header_callback;