diff --git a/ChangeLog b/ChangeLog
index f8b31c8b83..7661bea8ab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Apr  1 21:19:41 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* rational.c: need to include <float.h> just once.
+
 Tue Apr  1 16:40:21 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* bignum.c (big2dbl): more precise conversion at edge cases.
diff --git a/rational.c b/rational.c
index eccc73165f..3451fc65e5 100644
--- a/rational.c
+++ b/rational.c
@@ -7,6 +7,7 @@
 
 #include "ruby.h"
 #include <math.h>
+#include <float.h>
 
 #define NDEBUG
 #include <assert.h>
@@ -1110,8 +1111,6 @@ i_ilog2(VALUE x)
     return q + r;
 }
 
-#include <float.h>
-
 static VALUE
 nurat_to_f(VALUE self)
 {
@@ -1298,8 +1297,6 @@ integer_to_r(VALUE self)
     return rb_rational_new1(self);
 }
 
-#include <float.h>
-
 static VALUE
 float_decode(VALUE self)
 {