diff --git a/Documents/brltty.1.in b/Documents/brltty.1.in
index 49c392c..59f21bc 100644
--- a/Documents/brltty.1.in
+++ b/Documents/brltty.1.in
@@ -218,6 +218,9 @@ the first available MIDI output port
 \fB\-n\fR (\fB\-\-no\-daemon\fR)
 Remain in the foreground (useful for debugging).
 .TP
+\fB\-o \fIname\fB=\fIvalue\fB,\fR... (\fB\-\-override\-preference=\fR)
+Explicit preference settings.
+.TP
 \fB\-p \fIdevice\fR (\fB\-\-pcm\-device=\fR)
 The device to use for digital audio.
 For ALSA it's \fIname\fR[\fB:\fIargument\fB,\fR...].