diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index 559bdefbfb..f56dcca2cf 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -6505,7 +6505,7 @@ options {
 	      <listitem>
 		<para>
 		  If set, this is a shared secret used for generating
-		  and verifying Source Identity Token EDNS options
+		  and verifying EDNS COOKIE options
 		  within an anycast cluster.  If not set, the system
 		  will generate a random secret at startup.  The
 		  shared secret is encoded as a hex string and needs