diff --git a/README.md b/README.md
index ca53ef3..ca801c1 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 ## set up audio conversion
 
+for audio conversion the `playtzx` software is required
+
 - if on unix compile it yourself like this
   - download http://www.worldofspectrum.org/pub/sinclair/tools/unix/playtzx-0.12c.tar.gz
   - extract