diff --git a/source b/source
index c674496762c..4c67344ea69 100644
--- a/source
+++ b/source
@@ -56317,14 +56317,34 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
    <span>tree order</span> that is not <span data-x="concept-option-disabled">disabled</span>,
    if any, to true, and return.</p></li>
 
-   <li><p>If <var>element</var>'s <code data-x="attr-select-multiple">multiple</code> attribute is
-   absent, and two or more <code>option</code> elements in <var>element</var>'s <span
-   data-x="concept-select-option-list">list of options</span> have their <span
-   data-x="concept-option-selectedness">selectedness</span> set to true, then set the <span
-   data-x="concept-option-selectedness">selectedness</span> of all but the last <code>option</code>
-   element with its <span data-x="concept-option-selectedness">selectedness</span> set to true in
-   the <span data-x="concept-select-option-list">list of options</span> in <span>tree order</span>
-   to false.</p></li>
+   <li>
+    <p>If <var>element</var> has the <code data-x="attr-select-multiple">multiple</code> attribute,
+    then return.</p>
+
+   <li><p>Let <var>lastSeen</var> be false.</p></li>
+
+   <li>
+    <p>For each <var>option</var> in <var>element</var>'s <span
+    data-x="concept-select-option-list">list of options</span> in reverse order:</p>
+
+    <ol>
+     <li>
+      <p>If <var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
+      is true:</p>
+
+      <ol>
+       <li><p>If <var>option</var>'s <span>cached nearest ancestor <code>select</code>
+       element</span> is null, then <span>continue</span>.</p></li>
+
+       <li><p>If <var>lastSeen</var> is false, then set <var>lastSeen</var> to true and
+       <span>continue</span>.</p></li>
+
+       <li><p>Set <var>option</var>'s <span
+       data-x="concept-option-selectedness">selectedness</span> to false.</p></li>
+      </ol>
+     </li>
+    </ol>
+   </li>
   </ol>
   </div>