diff --git a/book/source/08-signing_components.md b/book/source/08-signing_components.md
index 29415ac..ff62e06 100644
--- a/book/source/08-signing_components.md
+++ b/book/source/08-signing_components.md
@@ -164,9 +164,9 @@ A [*direct key signature*](https://www.ietf.org/archive/id/draft-ietf-openpgp-cr
 
 In OpenPGP v6, a direct key signature is the [preferred mechanism](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#section-5.2.3.10-9).
 
-#### Primary User ID binding self-signature
+#### Self-signature binding to primary User ID
 
-In a certificate, one User ID serves as the [*primary* User ID](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-primary-user-id). The metadata in the binding self-signature on this User ID applies to the primary key of the certificate.
+In an OpenPGP certificate, one User ID serves as the [*primary* User ID](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-primary-user-id). The metadata in the binding self-signature on this User ID applies to the certificate's primary key.
 
 ### Revocation self-signatures: Invalidating components of a certificate