diff --git a/share/man/man4/uart.4 b/share/man/man4/uart.4
index 0d20c6d35c92..e5db31399ca1 100644
--- a/share/man/man4/uart.4
+++ b/share/man/man4/uart.4
@@ -121,6 +121,20 @@ Z8530: Zilog 8530 based serial communications controllers in asynchronous
 mode.
 .El
 .\"
+.Sh FILES
+.Bl -tag -width /dev/ttyu?.init -compact
+.It Pa /dev/ttyu?
+for callin ports
+.It Pa /dev/ttyu?.init
+.It Pa /dev/ttyu?.lock
+corresponding callin initial-state and lock-state devices
+.Pp
+.It Pa /dev/cuau?
+for callout ports
+.It Pa /dev/cuau?.init
+.It Pa /dev/cuau?.lock
+corresponding callout initial-state and lock-state devices
+.El
 .Sh SEE ALSO
 .Xr puc 4
 .\"