use macro for /usr/local/plan9
diff --git a/man/man3/fcall.3 b/man/man3/fcall.3
index 1143217..fe696a4 100644
--- a/man/man3/fcall.3
+++ b/man/man3/fcall.3
@@ -349,7 +349,7 @@
 The return value is 0 for end of file, or -1 for error; it does not return
 partial messages.
 .SH SOURCE
-.B /usr/local/plan9/src/lib9
+.B \*9/src/lib9
 .SH SEE ALSO
 .IR intro (3),
 .IR 9p (3),