diff --git a/webrtc.html b/webrtc.html
index ad5934b62..496f35c3f 100644
--- a/webrtc.html
+++ b/webrtc.html
@@ -2265,7 +2265,7 @@ <h3>Interface Definition</h3>
     readonly        attribute RTCSessionDescription?    remoteDescription;
     readonly        attribute RTCSessionDescription?    currentRemoteDescription;
     readonly        attribute RTCSessionDescription?    pendingRemoteDescription;
-    Promise&lt;void&gt;                      addIceCandidate (RTCIceCandidateInit candidate);
+    Promise&lt;void&gt;                      addIceCandidate (optional RTCIceCandidateInit candidate);
     readonly        attribute RTCSignalingState         signalingState;
     readonly        attribute RTCIceGatheringState      iceGatheringState;
     readonly        attribute RTCIceConnectionState     iceConnectionState;