diff --git a/content/notes/openbsd/index.md b/content/notes/openbsd/index.md
index e4f83d9..fc03e14 100644
--- a/content/notes/openbsd/index.md
+++ b/content/notes/openbsd/index.md
@@ -1,7 +1,7 @@
 ---
 title: OpenBSD notes
 date: 2023-11-29T20:33:48+0100
-lastmod: 2023-12-26T13:25:16+0000
+lastmod: 2023-12-30T22:03:53+0000
 tags:
 - openbsd
 - python
@@ -278,3 +278,13 @@ $ zmv -n -W '59-*' '*'
 mv -- 59-pat-winlink-on-openbsd pat-winlink-on-openbsd
 ~~~
 
+## Concatenate sound files (.wav)
+
+~~~console
+$ sox *.wav one-big-soundfile.wav
+~~~
+
+`cat *.wav > bigfile.wav` works too, but different. That would put all
+audio files into separate streams at the output file whereas `sox`
+appends one file after another in the big output file.
+