diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 8e8a9dbcc0c1..d71dd9324a09 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -471,8 +471,12 @@ pref("media.mediasource.whitelist", false);
 pref("media.mediasource.mp4.enabled", true);
 pref("media.mediasource.webm.enabled", false);
 
-// Enable new MediaSource architecture.
+#if defined(MOZ_WIDGET_GONK)
 pref("media.mediasource.format-reader", false);
+#else
+// Enable new MediaSource architecture.
+pref("media.mediasource.format-reader", true);
+#endif
 
 // Enable new MediaFormatReader architecture for webm in MSE
 pref("media.mediasource.format-reader.webm", false);