diff --git a/webrtc.html b/webrtc.html
index f31a14958..a151e38b8 100644
--- a/webrtc.html
+++ b/webrtc.html
@@ -5555,7 +5555,7 @@ <h4>
   constructor(RTCSessionDescriptionInit descriptionInitDict);
   readonly attribute RTCSdpType type;
   readonly attribute DOMString sdp;
-  [Default] object toJSON();
+  [Default] RTCSessionDescriptionInit toJSON();
 };</pre>
             <section>
               <h2>