diff --git a/url.bs b/url.bs
index 46b7f0b8..ee582110 100644
--- a/url.bs
+++ b/url.bs
@@ -3495,6 +3495,11 @@ null-or-<a>scalar value string</a> <var>base</var> (default null), and then runs
 </ol>
 </div>
 
+<div algorithm="URL/extract an origin">
+<p>Objects implementing the {{URL}} interface's <a for="platform object">extract an origin</a> steps are
+to return <a>this</a>'s <a for=URL>URL</a>'s <a for=url>origin</a>. [[!HTML]]
+</div>
+
 <hr>
 
 <div algorithm>