diff --git a/ed/idl/webrtc.idl b/ed/idl/webrtc.idl
index e571abb527f8..11cab622faef 100644
--- a/ed/idl/webrtc.idl
+++ b/ed/idl/webrtc.idl
@@ -503,7 +503,7 @@ enum RTCSctpTransportState {
   "closed"
 };
 
-[Exposed=Window]
+[Exposed=Window, Transferable]
 interface RTCDataChannel : EventTarget {
   readonly attribute USVString label;
   readonly attribute boolean ordered;