diff --git a/src/MDOutputHandler.php b/src/MDOutputHandler.php
index 397c0f2..4450684 100644
--- a/src/MDOutputHandler.php
+++ b/src/MDOutputHandler.php
@@ -31,15 +31,15 @@ class MDOutputHandler {
      * Function human_filesize translates byte-level filesizes to human readable ones.
      * Thanks to Jeffrey Sambells http://jeffreysambells.com/2012/10/25/human-readable-filesize-php
      *
-     * @param string  $bytes    A file size, e.g. returned from filesize().
+     * @param integer $bytes    A file size, e.g. returned from filesize().
      * @param integer $decimals Number of decimal digits to allow.
      *
      * @return string
      */
-    final private function _human_filesize(string $bytes, int $decimals = 2):string {
+    final private function _human_filesize(int $bytes, int $decimals = 2):string {
 
         $size = ['B','kB','MB','GB','TB','PB','EB','ZB','YB'];
-        $factor = floor((strlen($bytes) - 1) / 3);
+        $factor = floor((strlen((string)$bytes) - 1) / 3);
         return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) . $size[$factor];
 
     }