diff --git a/README.adoc b/README.adoc
index 908eef5..e9d5c77 100644
--- a/README.adoc
+++ b/README.adoc
@@ -52,6 +52,10 @@ ytdl_extra_args="--quiet"
 | *ytdl_extra_args* | Extra arguments for `youtube-dl`. Optional.
 |===============================================================================
 
+[WARNING]
+All old files in `download_dir` will be deleted. Don't put other files in the
+same directory!
+
 
 === feedlist