--- a/browser/app/Makefile.in
+++ b/browser/app/Makefile.in
@@ -99,8 +99,12 @@ tools repackage:: $(DIST)/bin/$(MOZ_APP_
 	cp -RL $(DIST)/branding/document.icns $(dist_dest)/Contents/Resources/document.icns
 	$(MKDIR) -p $(dist_dest)/Contents/Library/LaunchServices
 ifdef MOZ_UPDATER
 	mv -f $(dist_dest)/Contents/MacOS/updater.app/Contents/MacOS/org.mozilla.updater $(dist_dest)/Contents/Library/LaunchServices
 	ln -s ../../../../Library/LaunchServices/org.mozilla.updater $(dist_dest)/Contents/MacOS/updater.app/Contents/MacOS/org.mozilla.updater
 endif
 	printf APPLMOZB > $(dist_dest)/Contents/PkgInfo
 endif
+
+.PHONY: features
+tools features::
+	python -c 'import os, json; listing = {"system": os.listdir("$(DIST)/bin/browser/features")}; print json.dumps(listing)' > $(DIST)/bin/browser/chrome/browser/content/browser/built_in_addons.js