diff --git a/ch04_keys.adoc b/ch04_keys.adoc
index 407ed49c..9ec33000 100644
--- a/ch04_keys.adoc
+++ b/ch04_keys.adoc
@@ -775,7 +775,7 @@ public keys are known as _compressed public keys_, and the original 65-byte keys
 results in smaller transactions, allowing more payments to be made in the same
 block.
 
-As we saw in the section <<public_key_derivation>>, a public key is a point (x, y) on an
+As we saw in the section <<public_key_derivation>>, a public key is a point [.keep-together]#(x, y)# on an
 elliptic curve. Because the curve expresses a mathematical function, a
 point on the curve represents a solution to the equation and, therefore,
 if we know the _x_ coordinate, we can calculate the _y_ coordinate by