/* Carefully avoid adding any self-referential in-reply-to term. */
in_reply_to_message_id = _parse_message_id (message, in_reply_to, NULL);
- if (strcmp (in_reply_to_message_id,
+ if (in_reply_to_message_id &&
+ strcmp (in_reply_to_message_id,
notmuch_message_get_message_id (message)))
{
_notmuch_message_add_term (message, "replyto",