diff --git a/book/source/08-signing_components.md b/book/source/08-signing_components.md
index 24b7d7f..f946716 100644
--- a/book/source/08-signing_components.md
+++ b/book/source/08-signing_components.md
@@ -57,7 +57,7 @@ The **certify others** [key flag](https://www.ietf.org/archive/id/draft-ietf-ope
 The meaning of an OpenPGP signature depends significantly on its issuer. Self-signatures and third-party signatures, even when of the same type, serve distinct functions. For example:
 
 - Certifying self-signatures (type IDs `0x10` - `0x13`) bind a User ID to a certificate.
-- Third-party signatures of the same type IDs endorses the authenticity of a User ID.
+- Third-party signatures of the same type IDs endorse the authenticity of a User ID.
 
 In another instance: