diff --git a/emacs/notmuch-crypto.el b/emacs/notmuch-crypto.el
index 4035ee37..928de0bb 100644
--- a/emacs/notmuch-crypto.el
+++ b/emacs/notmuch-crypto.el
@@ -163,6 +163,7 @@ by user FROM."
       (recenter -1))))
 
 (declare-function notmuch-show-refresh-view "notmuch-show" (&optional reset-state))
+(declare-function notmuch-show-get-message-id "notmuch-show" (&optional bare))
 
 (defun notmuch-crypto--async-key-sentinel (process event)
   "When the user asks for a GPG key to be retrieved