diff --git a/ch04_keys.adoc b/ch04_keys.adoc
index 84707320..3389bc71 100644
--- a/ch04_keys.adoc
+++ b/ch04_keys.adoc
@@ -195,7 +195,7 @@ or
 
 The _mod p_ (modulo prime number _p_) indicates that this curve is over a
 finite field of prime order _p_, also written as latexmath:[\(
-\mathbb{F}_p\)], where i = 2^256^ – 2^32^ – 2^9^ – 2^8^ – 2^7^ – 2^6^ –
+\mathbb{F}_p\)], where _p_ = 2^256^ – 2^32^ – 2^9^ – 2^8^ – 2^7^ – 2^6^ –
 2^4^ – 1, a very large prime number.
 
 Because this curve is defined over a finite field of prime order instead