diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index 8d41efffdc..210301e250 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -2779,7 +2779,10 @@ function trailingslashit( $string ) {
  * @return string String without the trailing slashes.
  */
 function untrailingslashit( $string ) {
-	return rtrim( $string, '/\\' );
+	if ( ! empty( $string ) ) {
+		$string = rtrim( $string, '/\\' );
+	}
+	return $string;
 }
 
 /**