diff --git a/book/source/02-highlevel.md b/book/source/02-highlevel.md
index 35f3cb6..e455683 100644
--- a/book/source/02-highlevel.md
+++ b/book/source/02-highlevel.md
@@ -39,7 +39,7 @@ While PGP was first developed as commercial software, the owner at the time, PGP
 
 In July 1997, a process to produce an open standard under the then new name [OpenPGP](https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP) was started, resulting in [RFC 2440 "OpenPGP Message Format"](https://datatracker.ietf.org/doc/html/rfc2440), published in November 1998. RFC 2440 describes OpenPGP version 3.
 
-The name OpenPGP can be used freely by implementations, unlike the name PGP, which is a [registered trademark](https://uspto.report/TM/74685229)).
+The name OpenPGP can be used freely by implementations, unlike the name PGP, which is a [registered trademark](https://uspto.report/TM/74685229).
 
 ### GnuPG, an early Free Software implementation