diff --git a/lib/media-stream.js b/lib/media-stream.js
index <HASH>..<HASH> 100644
--- a/lib/media-stream.js
+++ b/lib/media-stream.js
@@ -14,6 +14,8 @@ function MediaStream (media, opts) {
   if (!(self instanceof MediaStream)) return new MediaStream(media, opts)
   stream.Writable.call(self, opts)
 
+  if (!MediaSource) throw new Error('web browser lacks MediaSource support')
+
   self.media = media
   opts = opts || {}
   opts.type = opts.type || 'video/webm; codecs="vorbis,vp8"'
detect browsers that lack MediaSource support