diff --git a/docs/man/man1/dumpkeys.1.in b/docs/man/man1/dumpkeys.1.in
index d3e894f..5c1d98e 100644
--- a/docs/man/man1/dumpkeys.1.in
+++ b/docs/man/man1/dumpkeys.1.in
@@ -164,6 +164,14 @@ output of
 .BI \-S shape " " " " \-\-shape= shape
 .LP
 .TP
+.B \-1 \-\-separate-lines
+This forces
+.B dumpkeys
+to write one line per (modifier,keycode) pair. It prefixes the word
+.I plain
+for plain keycodes.
+.LP
+.TP
 .B \-t \-\-funcs-only
 When this option is given,
 .B dumpkeys