use macro for /usr/local/plan9
diff --git a/man/man3/cputime.3 b/man/man3/cputime.3
index c88340d..78a93fa 100644
--- a/man/man3/cputime.3
+++ b/man/man3/cputime.3
@@ -25,4 +25,4 @@
 .I Times
 returns the elapsed real time, in milliseconds, that the process has been running.
 .SH SOURCE
-.B /usr/local/plan9/src/lib9/time.c
+.B \*9/src/lib9/time.c