diff --git a/ChangeLog b/ChangeLog
index 4a5724e3d5..8ed6fc14aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Aug 20 06:09:31 2008  Tanaka Akira  <akr@fsij.org>
+
+	* include/ruby/io.h (FMODE_TRUNC): value changed because 0x100 is used
+	  as FMODE_NOREVLOOKUP in socket.c
+
 Wed Aug 20 05:19:40 2008  Tanaka Akira  <akr@fsij.org>
 
 	* io.c (parse_mode_enc): extracted from mode_enc.
diff --git a/include/ruby/io.h b/include/ruby/io.h
index 391ada81f2..7312f4e9ab 100644
--- a/include/ruby/io.h
+++ b/include/ruby/io.h
@@ -81,9 +81,11 @@ typedef struct rb_io_t {
 #define FMODE_DUPLEX                    0x0020
 #define FMODE_APPEND                    0x0040
 #define FMODE_CREATE                    0x0080
-#define FMODE_TRUNC                     0x0100
+/* #define FMODE_NOREVLOOKUP            0x0100 */
 #define FMODE_WSPLIT                    0x0200
 #define FMODE_WSPLIT_INITIALIZED        0x0400
+#define FMODE_TRUNC                     0x0800
+/* #define FMODE_PREP                  0x10000 */
 
 #define GetOpenFile(obj,fp) rb_io_check_closed((fp) = RFILE(rb_io_taint_check(obj))->fptr)