diff --git a/book/source/02-highlevel.md b/book/source/02-highlevel.md
index 65de817..9c1d8f2 100644
--- a/book/source/02-highlevel.md
+++ b/book/source/02-highlevel.md
@@ -49,7 +49,7 @@ In 2007, [RFC 4880](https://datatracker.ietf.org/doc/html/rfc4880), defining ver
 
 Today multiple new Free Software implementations of OpenPGP play important roles:
 
-- Protonmail, who provide email encryption services for a large number of users, use (and maintain) [OpenPGP.js](https://openpgpjs.org/) as well as [GopenPGP](https://gopenpgp.org/).
+- Proton Mail, who provide email encryption services for a large number of users, use (and maintain) [OpenPGP.js](https://openpgpjs.org/) as well as [GopenPGP](https://gopenpgp.org/).
 - The Thunderbird email software is using the [RNP](https://www.rnpgp.org/) implementation for their built-in OpenPGP support since version 78 (released in mid-2020).
 - The RPM Package Manager software includes an OpenPGP backend based on [Sequoia PGP](https://sequoia-pgp.org/), a modern OpenPGP implementation in Rust. Fedora [uses Sequoia PGP in rpm](https://sequoia-pgp.org/blog/2023/04/27/rpm-sequoia/) since version 38.