diff --git a/mu4e/mu4e-view.el b/mu4e/mu4e-view.el
index d5d771cf..a3d96984 100644
--- a/mu4e/mu4e-view.el
+++ b/mu4e/mu4e-view.el
@@ -1416,7 +1416,7 @@ ATTNUM is nil ask for the attachment number."
         ;; server, and use it to determine the parent message (ie., the current
         ;; message) when showing the embedded message/rfc822, and return to the
         ;; current message when quitting that one.
-        (mu4e~view-temp-action docid index "mu4e" docid)
+        (mu4e~view-temp-action docid index 'mu4e (format "%s" docid))
       ;; otherwise, open with the default program (handled in mu-server
       (mu4e~proc-extract 'open docid index mu4e-decryption-policy))))