use macro for /usr/local/plan9
diff --git a/man/man1/map.1 b/man/man1/map.1
index d6363ff..a2d0985 100644
--- a/man/man1/map.1
+++ b/man/man1/map.1
@@ -637,7 +637,7 @@
 .B /bin/aux/mapd
 Map driver program
 .SH SOURCE
-.B /usr/local/plan9/src/cmd/map
+.B \*9/src/cmd/map
 .SH "SEE ALSO"
 .IR map (7), 
 .IR plot (1)