diff --git a/lisp/net/browse-url.el b/lisp/net/browse-url.el
index a4d47f6..dca81fe 100644
--- a/lisp/net/browse-url.el
+++ b/lisp/net/browse-url.el
@@ -1597,7 +1597,8 @@ used instead of `browse-url-new-window-flag'."
           (if (not mml-mode)
               (error "Enable MML mode if you want to attach files")
             (dolist (attach attaches)
-              (mml-attach-file attach nil nil "attachment"))))))))
+              (mml-attach-file attach (mm-default-file-encoding attach)
+                               nil "attachment"))))))))
 
 ;; --- Random browser ---