diff --git a/README.md b/README.md
index 28edcc7..2194940 100644
--- a/README.md
+++ b/README.md
@@ -5,8 +5,15 @@ This repository is a mirror of SunVox 1.3b sources provided
 by original developer NightRadio under a BSD license:
 http://sunvox.blogspot.co.uk/2015/09/all-sunvox-versions-from-2008.html
 
+This included only the SunDog engine (multi-platform toolkit for building apps)
+and the SunVox engine (the synthesizer), but NOT the SunVox UI and app itself.
+
+This means you can use this to build apps playing or producing SunVox
+files using the same UI toolkit, but you won't be able to just build
+the exact same SunVox application.
+
 Versions 1.4 and later are closed-source.
 You can download them from: http://www.warmplace.ru/soft/sunvox/
 
 Feel free to use this source code to make an open source fork of SunVox 
-or use the SunVox engine in your project/video game/etc.
+or use the SunVox engine in your project/video game/etc. :)