diff --git a/index.html b/index.html
index d7e4ac9..765516e 100644
--- a/index.html
+++ b/index.html
@@ -893,7 +893,7 @@ <h3>Supporting algorithms</h3>
         To determine the <dfn>owning global object set</dfn> for a {{WorkerGlobalScope}} |workerGlobalScope|:
         <ol>
           <li>
-            Let |owningGlobalObjectSet| be am empty set.
+            Let |owningGlobalObjectSet| be an empty [=set=].
           </li>
           <li>
             [=list/For each=] |owner| in |workerGlobalScope|'s [=WorkerGlobalScope/owner set=]: