--- a/notmuch-show.el	2017-11-09 21:17:05.791414308 +0100
+++ b/notmuch-show.el	2017-11-09 21:17:57.958437388 +0100
@@ -2011,20 +2011,21 @@
 (defun notmuch-show-view-raw-message ()
   "View the original source of the current message."
   (interactive)
   (let* ((id (notmuch-show-get-message-id))
 	 (buf (get-buffer-create (concat "*notmuch-raw-" id "*")))
 	 (inhibit-read-only t))
     (switch-to-buffer buf)
     (erase-buffer)
     (let ((coding-system-for-read 'no-conversion))
       (call-process notmuch-command nil t nil "show" "--format=raw" id))
+    (save-excursion (icalendar--clean-up-line-endings))
     (goto-char (point-min))
     (set-buffer-modified-p nil)
     (setq buffer-read-only t)
     (view-buffer buf 'kill-buffer-if-not-modified)))
 
 (defun notmuch-show-resume-message ()
   "Resume EDITING the current draft message."
   (interactive)
   (notmuch-draft-resume (notmuch-show-get-message-id)))