diff --git a/book/source/17-zoom_certificates.md b/book/source/17-zoom_certificates.md
index 34125ec..2ba5db6 100644
--- a/book/source/17-zoom_certificates.md
+++ b/book/source/17-zoom_certificates.md
@@ -4,7 +4,7 @@ SPDX-License-Identifier: CC-BY-SA-4.0
 -->
 
 (zoom_certificates)=
-# Zooming in: Packet structure of certificates and keys
+# Zooming in: Packet structure of certificates
 
 Now that we've established the concepts and  components that make up OpenPGP certificates , let's look at the internal details of an example certificate.