diff --git a/dom.bs b/dom.bs
index f833ab643..19bb0d18d 100644
--- a/dom.bs
+++ b/dom.bs
@@ -1478,6 +1478,10 @@ controller.abort();</code></pre>
 
  <pre><code class=lang-javascript>
 function doAmazingness({signal}) {
+  if (signal.aborted) {
+    return Promise.reject(new DOMException('Aborted', 'AbortError'));
+  }
+
   return new Promise((resolve, reject) => {
     // Begin doing amazingness, and call resolve(result) when done.
     // But also, watch for signals: