diff --git a/ChangeLog b/ChangeLog
index 59826aa654..a6706273ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Aug 27 15:26:33 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* file.c (null_device): move from io.c.
+
 Fri Aug 27 12:47:44 2010  Kenta Murata  <mrkn@mrkn.jp>
 
 	* math.c (math_atan2): change the behavior when x and y are zero.
diff --git a/NEWS b/NEWS
index 735841d99b..da183e4788 100644
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,7 @@ with all sufficient information, see the ChangeLog file.
 
   * Float
     * new constants:
-      * IO::NULL
+      * File::NULL
         name of NULL device.
 
 * io/console
diff --git a/file.c b/file.c
index 962fa9ac4e..8da764a4c2 100644
--- a/file.c
+++ b/file.c
@@ -5191,6 +5191,17 @@ define_filetest_function(const char *name, VALUE (*func)(ANYARGS), int argc)
     rb_define_singleton_method(rb_cFile, name, func, argc);
 }
 
+static const char null_device[] =
+#if defined DOSISH
+    "NUL"
+#elif defined AMIGA || defined __amigaos__
+    "NIL"
+#elif defined __VMS
+    "NL:"
+#else
+    "/dev/null"
+#endif
+    ;
 
 /*
  *  A <code>File</code> is an abstraction of any file object accessible
@@ -5327,6 +5338,8 @@ Init_File(void)
     rb_file_const("LOCK_UN", INT2FIX(LOCK_UN));
     rb_file_const("LOCK_NB", INT2FIX(LOCK_NB));
 
+    rb_file_const("NULL", rb_obj_freeze(rb_usascii_str_new2(null_device)));
+
     rb_define_method(rb_cFile, "path",  rb_file_path, 0);
     rb_define_method(rb_cFile, "to_path",  rb_file_path, 0);
     rb_define_global_function("test", rb_f_test, -1);
diff --git a/io.c b/io.c
index ea6b2a2f23..459528255e 100644
--- a/io.c
+++ b/io.c
@@ -9639,18 +9639,6 @@ rb_get_argv(void)
     return ARGF.argv;
 }
 
-static const char null_device[] =
-#if defined DOSISH
-    "NUL"
-#elif defined AMIGA || defined __amigaos__
-    "NIL"
-#elif defined __VMS
-    "NL:"
-#else
-    "/dev/null"
-#endif
-    ;
-
 /*
  * Document-class: IOError
  *
@@ -9984,8 +9972,6 @@ Init_IO(void)
     rb_define_method(rb_cIO, "autoclose?", rb_io_autoclose_p, 0);
     rb_define_method(rb_cIO, "autoclose=", rb_io_set_autoclose, 1);
 
-    rb_define_const(rb_cIO, "NULL", rb_obj_freeze(rb_usascii_str_new2(null_device)));
-
     rb_define_variable("$stdin", &rb_stdin);
     rb_stdin = prep_stdio(stdin, FMODE_READABLE, rb_cIO, "<STDIN>");
     rb_define_hooked_variable("$stdout", &rb_stdout, 0, stdout_setter);