use macro for /usr/local/plan9
diff --git a/man/man3/getns.3 b/man/man3/getns.3
index cc76f2b..b2e03f9 100644
--- a/man/man3/getns.3
+++ b/man/man3/getns.3
@@ -17,6 +17,6 @@
 .IR intro (4)
 for details.
 .SH SOURCE
-.B /usr/local/plan9/src/lib9/getns.c
+.B \*9/src/lib9/getns.c
 .SH SEE ALSO
 .IR intro (4)