use macro for /usr/local/plan9
diff --git a/man/man3/elgamal.3 b/man/man3/elgamal.3
index 204b85e..2fc75ac 100644
--- a/man/man3/elgamal.3
+++ b/man/man3/elgamal.3
@@ -111,7 +111,7 @@
 .I egsigfree
 are provided to manage signature storage.
 .SH SOURCE
-.B /usr/local/plan9/src/libsec
+.B \*9/src/libsec
 .SH SEE ALSO
 .IR mp (3),
 .IR aes (3),