use macro for /usr/local/plan9
diff --git a/man/man1/proof.1 b/man/man1/proof.1
index 01e8e35..27662d0 100644
--- a/man/man1/proof.1
+++ b/man/man1/proof.1
@@ -124,7 +124,7 @@
 how to convert troff output fonts and character names
 into screen fonts and character numbers
 .SH SOURCE
-.B /usr/local/plan9/src/cmd/proof
+.B \*9/src/cmd/proof
 .SH SEE ALSO
 .IR lp (1), 
 .IR gs (1),