diff --git a/wp-includes/compat.php b/wp-includes/compat.php
index b08c5654c..004386500 100644
--- a/wp-includes/compat.php
+++ b/wp-includes/compat.php
@@ -77,13 +77,13 @@ function hash_hmac($algo, $data, $key, $raw_output = false) {
 }
 endif;
 
-if ( ! function_exists('mb_strcut') ):
-	function mb_strcut( $str, $start, $length=null, $encoding=null ) {
-		return _mb_strcut($str, $start, $length, $encoding);
+if ( ! function_exists('mb_substr') ):
+	function mb_substr( $str, $start, $length=null, $encoding=null ) {
+		return _mb_substr($str, $start, $length, $encoding);
 	}
 endif;
 
-function _mb_strcut( $str, $start, $length=null, $encoding=null ) {
+function _mb_substr( $str, $start, $length=null, $encoding=null ) {
 	// the solution below, works only for utf-8, so in case of a different
 	// charset, just use built-in substr
 	$charset = get_option( 'blog_charset' );