diff --git a/index.html b/index.html
index 811b0726..af60f7fc 100644
--- a/index.html
+++ b/index.html
@@ -206,8 +206,12 @@ <h2>
         <dfn>PaymentRequest</dfn> interface
       </h2>
       <pre class="idl">
-        [Constructor(sequence&lt;PaymentMethodData&gt; methodData, PaymentDetails details, optional PaymentOptions options),
-        SecureContext]
+        [Constructor(
+          optional DOMString paymentRequestID, 
+          sequence&lt;PaymentMethodData&gt; methodData, 
+          PaymentDetails details, 
+          optional PaymentOptions options
+         ), SecureContext]
         interface PaymentRequest : EventTarget {
           Promise&lt;PaymentResponse&gt; show();
           Promise&lt;void&gt; abort();
@@ -277,7 +281,7 @@ <h2>
           Constructor
         </h2>
         <p>
-          The <a>PaymentRequest</a> is constructed using the supplied
+          The <a>PaymentRequest</a> is constructed using the supplied <var>paymentRequestID</var>,
           <var>methodData</var> list including any <a>payment method</a>
           specific <a data-lt="PaymentMethodData.data">data</a>, the payment
           <var>details</var>, and the payment <var>options</var>. The
@@ -556,6 +560,8 @@ <h2>
           </li>
           <li>Let <var>request</var> be a new <a>PaymentRequest</a>.
           </li>
+          <li>Set <var>request</var>.<a>[[\paymentRequestID]]</a> to <var>paymentRequestID</var>.
+          </li>
           <li>Set <var>request</var>.<a>[[\options]]</a> to <var>options</var>.
           </li>
           <li>Set <var>request</var>.<a>[[\state]]</a> to <i>created</i>.
@@ -842,6 +848,14 @@ <h2>
               Description (<em>non-normative</em>)
             </th>
           </tr>
+          <tr>
+            <td>
+              <dfn>[[\paymentRequestID]]</dfn>
+            </td>
+            <td>
+              The <code>paymentRequestID</code> supplied or generated during construction.
+            </td>
+          </tr>
           <tr>
             <td>
               <dfn>[[\serializedMethodData]]</dfn>