diff --git a/src/PDF.php b/src/PDF.php
index 715ddd4..6fd13e8 100644
--- a/src/PDF.php
+++ b/src/PDF.php
@@ -169,7 +169,8 @@ public function download($filename = 'document.pdf' ){
         $output = $this->output();
         return new Response($output, 200, array(
                 'Content-Type' => 'application/pdf',
-                'Content-Disposition' =>  'attachment; filename="'.$filename.'"'
+                'Content-Disposition' =>  'attachment; filename="'.$filename.'"',
+                'Content-Length' => strlen($output),
             ));
     }