diff --git a/ch11_blockchain.adoc b/ch11_blockchain.adoc
index 4aa0ff00..cb18fb1a 100644
--- a/ch11_blockchain.adoc
+++ b/ch11_blockchain.adoc
@@ -68,7 +68,7 @@ infinitesimal.
 
 === Structure of a Block
 
-A block is a container data structure that aggregates
+A block ((("blocks", "structure of")))is a container data structure that aggregates
 transactions for inclusion in the blockchain. The
 block is made of a header, containing metadata, followed by a long list
 of transactions that make up the bulk of its size. The block header is