diff --git a/dom/media/tests/mochitest/test_enumerateDevices.html b/dom/media/tests/mochitest/test_enumerateDevices.html
index 7db3c894c474..9582d91c15fa 100644
--- a/dom/media/tests/mochitest/test_enumerateDevices.html
+++ b/dom/media/tests/mochitest/test_enumerateDevices.html
@@ -34,6 +34,9 @@ runTest(() =>
       ok(d.label.length !== undefined, "Device label: " + d.label);
       is(d.groupId, "", "Don't support groupId yet");
     });
+    var jsoned = JSON.parse(JSON.stringify(devices));
+    is(jsoned[0].kind, devices[0].kind, "kind survived serializer");
+    is(jsoned[0].deviceId, devices[0].deviceId, "deviceId survived serializer");
   })
   // Check deviceId failure paths for video.
   .then(() => mustSucceed("unknown plain deviceId on video",
diff --git a/dom/webidl/MediaDeviceInfo.webidl b/dom/webidl/MediaDeviceInfo.webidl
index fe28aa5bab6d..b42519ad1319 100644
--- a/dom/webidl/MediaDeviceInfo.webidl
+++ b/dom/webidl/MediaDeviceInfo.webidl
@@ -19,4 +19,6 @@ interface MediaDeviceInfo {
   readonly attribute MediaDeviceKind kind;
   readonly attribute DOMString       label;
   readonly attribute DOMString       groupId;
+
+  jsonifier;
 };