diff --git a/book/source/04-certificates.md b/book/source/04-certificates.md
index d7b3c03..18f20b9 100644
--- a/book/source/04-certificates.md
+++ b/book/source/04-certificates.md
@@ -594,7 +594,7 @@ So, there is some tension between the goals of
 - privacy related goals (also see {ref}`email-lookup`, for a comparison of certificate distribution mechanisms, which also touches on this theme).
 
 (unbound_user_ids)=
-### Adding unbound, local, User IDs to a certificate
+### Adding unbound, local User IDs to a certificate
 
 Some OpenPGP software may add User IDs to a certificate, which are not bound to the primary key by the certificate's owner. This can be useful to store local identity information (e.g., Sequoia's public store attaches ["pet-names"][PET] to certificates, in this way).