diff --git a/scroll-animations-1/Overview.bs b/scroll-animations-1/Overview.bs
index ee0a6c68c2de..fe6f7ad2f3a7 100644
--- a/scroll-animations-1/Overview.bs
+++ b/scroll-animations-1/Overview.bs
@@ -761,7 +761,7 @@ spec: cssom-view-1; type: dfn;
 	The CSS ''@keyframes'' rule is extended thus:
 
 	<pre class="prod">
-		<<keyframe-selector>> = from | to | <<percentage>> | <<timeline-range-name>> <<percentage>>
+		<<keyframe-selector>> = from | to | <<percentage [0,100]>> | <<timeline-range-name>> <<percentage>>
 	</pre>
 
 	where <<timeline-range-name>> is the [=CSS identifier=]