diff --git a/wp-includes/link-template.php b/wp-includes/link-template.php
index 2ef9d54..02b1a3b 100644
--- a/wp-includes/link-template.php
+++ b/wp-includes/link-template.php
@@ -1935,7 +1935,7 @@ function get_site_url( $blog_id = null, $path = '', $scheme = null ) {
  * @return string Admin url link with optional path appended
 */
 function admin_url( $path = '', $scheme = 'admin' ) {
-	return get_admin_url(null, $path, $scheme);
+	return (string)get_admin_url(null, $path, $scheme);
 }
 
 /**