use macro for /usr/local/plan9
diff --git a/man/man3/stat.3 b/man/man3/stat.3
index 03f3abe..ff2ac25 100644
--- a/man/man3/stat.3
+++ b/man/man3/stat.3
@@ -277,7 +277,7 @@
 .I stat
 to retrieve the initial values first.
 .SH SOURCE
-.B /usr/local/plan9/src/lib9/dirstat.c
+.B \*9/src/lib9/dirstat.c
 .SH SEE ALSO
 .IR intro (3),
 .IR fcall (3),