diff --git a/ChangeLog b/ChangeLog
index a0dc2d4fb9..8c25b92c94 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Feb  4 19:14:27 2011  Tanaka Akira  <akr@fsij.org>
+
+	* enc/trans/utf8_mac.trans: parenthesize macro arguments.
+
 Fri Feb  4 12:11:51 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* string.c (str_utf8_nth): fixed a conditon of optimized lead
diff --git a/enc/trans/utf8_mac.trans b/enc/trans/utf8_mac.trans
index 0d69dba46a..8ea0afd73f 100644
--- a/enc/trans/utf8_mac.trans
+++ b/enc/trans/utf8_mac.trans
@@ -52,7 +52,7 @@ struct from_utf8_mac_status {
     int end;
     int len;
 };
-#define buf_length(sp) (sp->len)
+#define buf_length(sp) ((sp)->len)
 
 int
 buf_bytesize(struct from_utf8_mac_status *sp)