diff --git a/spec/locales-currencies-tz.html b/spec/locales-currencies-tz.html
index 643b8630..03d30e16 100644
--- a/spec/locales-currencies-tz.html
+++ b/spec/locales-currencies-tz.html
@@ -118,7 +118,7 @@ <h1>
       </h1>
       <dl class="header">
         <dt>description</dt>
-        <dd>The returned String value represents the structurally valid (<emu-xref href="#sec-isstructurallyvalidlanguagetag"></emu-xref>) and canonicalized (<emu-xref href="#sec-canonicalizeunicodelocaleid"></emu-xref>) language tag for the host environment's current locale.</dd>
+        <dd>The returned String value represents the structurally valid (<emu-xref href="#sec-isstructurallyvalidlanguagetag"></emu-xref>) and canonicalized (<emu-xref href="#sec-canonicalizeunicodelocaleid"></emu-xref>) language tag for the host environment's current locale. It must not contain a Unicode locale extension sequence.</dd>
       </dl>
     </emu-clause>
   </emu-clause>