diff --git a/webrtc.html b/webrtc.html
index b448f2aad..83fec1e08 100644
--- a/webrtc.html
+++ b/webrtc.html
@@ -4367,7 +4367,7 @@ <h3>RTCRtpSender Interface</h3>
       <div>
         <pre class="idl">interface RTCRtpSender {
     readonly        attribute MediaStreamTrack? track;
-    readonly        attribute RTCDtlsTransport  transport;
+    readonly        attribute RTCDtlsTransport?  transport;
     readonly        attribute RTCDtlsTransport? rtcpTransport;
     static RTCRtpCapabilities getCapabilities (DOMString kind);
     Promise&lt;void&gt;             setParameters (optional RTCRtpParameters parameters);
@@ -4386,7 +4386,7 @@ <h2>Attributes</h2>
               associated with this <code><a>RTCRtpSender</a></code> object.</p>
             </dd>
             <dt><dfn><code>transport</code></dfn> of type <span class=
-            "idlAttrType"><a>RTCDtlsTransport</a></span>, readonly</dt>
+            "idlAttrType"><a>RTCDtlsTransport</a></span>, readonly, nullable</dt>
             <dd>
               <p>The <code>transport</code> attribute is the transport over
               which media from <code>track</code> is sent in the form of RTP
@@ -5064,7 +5064,7 @@ <h3>RTCRtpReceiver Interface</h3>
       <div>
         <pre class="idl">interface RTCRtpReceiver {
     readonly        attribute MediaStreamTrack  track;
-    readonly        attribute RTCDtlsTransport  transport;
+    readonly        attribute RTCDtlsTransport?  transport;
     readonly        attribute RTCDtlsTransport? rtcpTransport;
     static RTCRtpCapabilities          getCapabilities (DOMString kind);
     RTCRtpParameters                   getParameters ();
@@ -5082,7 +5082,7 @@ <h2>Attributes</h2>
               object.</p>
             </dd>
             <dt><code>transport</code> of type <span class=
-            "idlAttrType"><a>RTCDtlsTransport</a></span>, readonly</dt>
+            "idlAttrType"><a>RTCDtlsTransport</a></span>, readonly, nullable</dt>
             <dd>
               <p>The <dfn><code>transport</code></dfn> attribute is the
               transport over which media for the receiver's <code>track</code>
@@ -5434,7 +5434,10 @@ <h3>RTCDtlsTransport Interface</h3>
       SCTP packets sent and received by data channels. In particular, DTLS adds
       security to an underlying transport, and the
       <code>RTCDtlsTransport</code> interface allows access to information
-      about the underlying transport and the security added.</p>
+      about the underlying transport and the security added.
+      <code><a>RTCDtlsTransport</a></code> objects are constructed
+      as a result of calls to <code>setLocalDescription()</code>
+      and <code>setRemoteDescription()</code>.</p>
       <div>
         <pre class="idl">interface RTCDtlsTransport {
     readonly        attribute RTCIceTransport       transport;
@@ -5540,7 +5543,9 @@ <h3>RTCIceTransport Interface</h3>
       application access to information about the ICE transport over which
       packets are sent and received. In particular, ICE manages peer-to-peer
       connections which involve state which the application may want to
-      access.</p>
+      access. <code><a>RTCIceTransport</a></code> objects are constructed
+      as a result of calls to <code>setLocalDescription()</code>
+      and <code>setRemoteDescription()</code>.</p>
       <div>
         <pre class="idl">interface RTCIceTransport {
     readonly        attribute RTCIceRole           role;