diff --git a/doc/lp-set-dup.1 b/doc/lp-set-dup.1
index 03d3217..404b451 100644
--- a/doc/lp-set-dup.1
+++ b/doc/lp-set-dup.1
@@ -3,7 +3,8 @@
 lp\-set\-dup \- mark one or more bugs as duplicate of another bug
 
 .SH SYNOPSIS
-.B lp\-set\-dup [\-f] <main bug> <duplicate bug> [<duplicate bug> ...]
+.B lp\-set\-dup \fR[\fB\-f\fR] <\fImain bug\fR> <\fIduplicate bug\fR>
+[<\fIduplicate bug\fR> ...]
 .br
 .B lp\-set\-dup \-\-help