use macro for /usr/local/plan9
diff --git a/man/man3/setjmp.3 b/man/man3/setjmp.3
index 0ed7845..e2af559 100644
--- a/man/man3/setjmp.3
+++ b/man/man3/setjmp.3
@@ -86,7 +86,7 @@
 }
 .EE
 .SH SOURCE
-.B /usr/local/plan9/src/lib9/jmp.c
+.B \*9/src/lib9/jmp.c
 .SH SEE ALSO
 .IR notify (3)
 .SH BUGS