diff --git a/webrtc.html b/webrtc.html
index 3ed319633..ae32a9a25 100644
--- a/webrtc.html
+++ b/webrtc.html
@@ -7049,8 +7049,8 @@ <h2>
                   </li>
                   <li>
                     <p>
-                      Let <var>expires</var> be a {{EpochTimeStamp}} value of
-                      2592000000.
+                      Let <var>expires</var> be a value of
+                      2592000000 (30*24*60*60*1000)
                     </p>
                     <div class="note">
                       <p>
@@ -7235,21 +7235,22 @@ <h2>
             {{RTCPeerConnection/generateCertificate}}.
           </p>
           <pre class="idl">dictionary RTCCertificateExpiration {
-  [EnforceRange] EpochTimeStamp expires;
+  [EnforceRange] unsigned long long expires;
 };</pre>
           <dl data-link-for="RTCCertificateExpiration" data-dfn-for=
           "RTCCertificateExpiration" class="methods">
             <dt data-tests=
             "RTCPeerConnection-generateCertificate.html,RTCCertificate.html">
-              <dfn>expires</dfn>, of type {{EpochTimeStamp}}
+              <dfn>expires</dfn>, of type unsigned long long
             </dt>
             <dd>
               <p>
                 An optional {{expires}} attribute MAY be added to the
                 definition of the algorithm that is passed to
                 {{RTCPeerConnection/generateCertificate}}. If this parameter is
-                present it indicates the maximum time that the
-                {{RTCCertificate}} is valid for relative to the current time.
+                present it indicates the maximum time in milliseconds that the
+                {{RTCCertificate}} is valid for, measured from the time the
+                certificate is created.
               </p>
             </dd>
           </dl>