diff --git a/libsndio/mio_open.3 b/libsndio/mio_open.3
index 06a854d..164560b 100644
--- a/libsndio/mio_open.3
+++ b/libsndio/mio_open.3
@@ -247,3 +247,8 @@ may be a value between 0 and 2.
 .Xr midi 4 ,
 .Xr sndio 7 ,
 .Xr sndiod 8
+.Sh HISTORY
+These functions first appeared in
+.Ox 4.7 .
+.Sh AUTHORS
+.An Alexandre Ratchov Aq Mt ratchov@openbsd.org