diff --git a/doc/arm/Bv9ARM.ch06.html b/doc/arm/Bv9ARM.ch06.html
index 54f56b4729..ee63cc72e0 100644
--- a/doc/arm/Bv9ARM.ch06.html
+++ b/doc/arm/Bv9ARM.ch06.html
@@ -6562,7 +6562,7 @@ example.com                 CNAME   rpz-tcp-only.
             Requests for any and all undefined subdomains of a given
             valid domain result in NXDOMAIN errors, and are identical
             regardless of query type.
-            They are limited by <span><strong class="command">nxdomain-per-second</strong></span>
+            They are limited by <span><strong class="command">nxdomains-per-second</strong></span>
             (default base <span><strong class="command">responses-per-second</strong></span>).
             This controls some attacks using random names, but
             can be relaxed or turned off (set to 0)