diff --git a/book/source/17-zoom_certificates.md b/book/source/17-zoom_certificates.md
index 6ac2d63..7aa35d2 100644
--- a/book/source/17-zoom_certificates.md
+++ b/book/source/17-zoom_certificates.md
@@ -402,7 +402,7 @@ Notice that the structure of this *Public-Subkey packet* mirrors the primary key
 
 ### Subkey binding signature
 
-The aforementioned subkey packet is disconnected from the OpenPGP certificate to which it belongs. The link between the subkey and the complete OpenPGP key is made with a cryptographic signature, generated by primary key of the OpenPGP certificate.
+The aforementioned subkey packet is disconnected from the OpenPGP certificate to which it belongs. The link between the subkey and the complete OpenPGP certificate is made with a cryptographic signature, generated by primary key of the OpenPGP certificate.
 
 The type of signature is called a *subkey binding signature*, because it "binds" or connects the subkey to the rest of the key.