Many small edits.
diff --git a/man/man3/dup.3 b/man/man3/dup.3
index a9378dc..392e6fe 100644
--- a/man/man3/dup.3
+++ b/man/man3/dup.3
@@ -31,8 +31,9 @@
 Sets
 .IR errstr .
 .SH BUGS
-.I Dup
-is a macro for
-.I p9dup
-to avoid name conflicts with the Unix function; see
+To avoid name conflicts with the underlying system,
+.I dup
+is a preprocessor macro defined as
+.IR p9dup ;
+see
 .IR intro (3).