diff --git a/ch02.asciidoc b/ch02.asciidoc
index e205ebd8..feafe9b1 100644
--- a/ch02.asciidoc
+++ b/ch02.asciidoc
@@ -42,7 +42,7 @@ $1.50 USD
 
 ((("millibits")))Bob says, "That's one-dollar-fifty, or fifteen millibits."
 
-((("payment requests")))Bob's point-of-sale system will also automatically create a special QR code containing a _payment request_ (see <<payment-request-QR>>).
+((("payment requests")))((("QR codes", "payment requests")))Bob's point-of-sale system will also automatically create a special QR code containing a _payment request_ (see <<payment-request-QR>>).
 
 Unlike a QR code that simply contains a destination bitcoin address, a payment request is a QR-encoded URL that contains a destination address, a payment amount, and a generic description such as "Bob's Cafe." This allows a bitcoin wallet application to pre-fill the information used to send the payment while showing a human-readable description to the user. You can scan the QR code with a bitcoin wallet application to see what Alice would see.