diff --git a/book/source/06-signatures.md b/book/source/06-signatures.md
index bf7efb7..cbb0e92 100644
--- a/book/source/06-signatures.md
+++ b/book/source/06-signatures.md
@@ -26,7 +26,7 @@ In this document, "signature" will refer to OpenPGP signature packets.
 (signature_types)=
 ## Signature types in OpenPGP
 
-The OpenPGP standard defines a set of [Signature types](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-signature-types), each identified by a numerical *signature type ID*. Signature types define the purpose of a signature and how it should be interpreted.
+The OpenPGP standard defines a set of [Signature types](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-signature-types), each identified by a numerical *signature type ID*. Signature types define the purpose of a signature packet and how it should be interpreted.
 
 Signature types can be predominantly classified in two ways: