--- a/dom/media/MediaPrefs.h
+++ b/dom/media/MediaPrefs.h
@@ -170,17 +170,17 @@ private:
   // Flac
   DECL_MEDIA_PREF("media.ogg.flac.enabled",                   FlacInOgg, bool, false);
   DECL_MEDIA_PREF("media.flac.enabled",                       FlacEnabled, bool, true);
 
 #if !defined(RELEASE_OR_BETA)
   DECL_MEDIA_PREF("media.rust.test_mode",                     RustTestMode, bool, false);
 #endif
 
-#if defined(OS_LINUX)
+#if defined(MOZ_WIDGET_GTK)
   DECL_MEDIA_PREF("media.rust.mp4parser",                     EnableRustMP4Parser, bool, true);
 #else
   DECL_MEDIA_PREF("media.rust.mp4parser",                     EnableRustMP4Parser, bool, false);
 #endif
 
   // Error/warning handling, Decoder Doctor
   DECL_MEDIA_PREF("media.playback.warnings-as-errors",        MediaWarningsAsErrors, bool, false);
   DECL_MEDIA_PREF("media.playback.warnings-as-errors.stagefright-vs-rust",