diff --git a/book/source/02-highlevel.md b/book/source/02-highlevel.md
index 3dbbb26..19bb393 100644
--- a/book/source/02-highlevel.md
+++ b/book/source/02-highlevel.md
@@ -65,7 +65,7 @@ Some implementations explored other non-standardized extensions. Notably, algori
 Today, multiple implementations of OpenPGP play important roles:
 
 - Proton Mail, which provides email encryption services for a large number of users, uses and maintains [OpenPGP.js](https://openpgpjs.org/) as well as [GopenPGP](https://gopenpgp.org/), an OpenPGP wrapper library written in golang.
-- The Mozilla Thunderbird email software uses [RNP](https://www.rnpgp.org/), its C++ implementation of OpenPGP.
+- The Mozilla Thunderbird email software uses [RNP](https://www.rnpgp.org/), a C++ implementation of OpenPGP.
 - The RPM Package Manager software includes an OpenPGP backend based on [Sequoia PGP](https://sequoia-pgp.org/), a modern OpenPGP implementation written in Rust. The Fedora operating system, Fedora Linux 38, [uses Sequoia PGP in rpm](https://sequoia-pgp.org/blog/2023/04/27/rpm-sequoia/).
 
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