diff --git a/spec/index.html b/spec/index.html
index 0ee9952..6270374 100644
--- a/spec/index.html
+++ b/spec/index.html
@@ -8,6 +8,19 @@
 copyright: proposal
 contributors: Dean Tribble, Till Schneidereit, Sathya Gunasekaran
 </pre>
+<style>
+[normative-optional] {
+  border-left: 5px solid #ff6600;
+  padding: .5em;
+  display: block;
+  background: #ffeedd;
+}
+[normative-optional]:before {
+  display: block;
+  color: #884400;
+  content: "NORMATIVE OPTIONAL";
+}
+</style>
 
 <emu-import href="./weak-ref.html"></emu-import>
 <emu-import href="./finalization-group.html"></emu-import>
diff --git a/spec/weak-ref.html b/spec/weak-ref.html
index fa21751..faa910e 100644
--- a/spec/weak-ref.html
+++ b/spec/weak-ref.html
@@ -89,6 +89,18 @@ <h1>Properties of the WeakRef Prototype Object</h1>
       <li>does not have a [[Target]] internal slot.</li>
     </ul>
 
+    <emu-clause id="sec-weak-ref.prototype.constructor" normative-optional>
+      <h1>WeakRef.prototype.constructor</h1>
+
+      <p>The initial value of `WeakRef.prototype.constructor` is the intrinsic object %WeakRef%.</p>
+
+      <p>This property has the attributes { [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.</p>
+
+      <emu-note type="editor">
+        This section is to be treated identically to the "Annex B" of ECMA-262, but to be written in-line with the main specification.
+      </emu-note>
+    </emu-clause>
+
     <emu-clause id="sec-weak-ref.prototype.deref">
       <h1>WeakRef.prototype.deref ( )</h1>
       <p>The following steps are taken:</p>