diff --git a/ChangeLog b/ChangeLog
index e839fd9963..5436581640 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -24,6 +24,13 @@ Wed Dec 31 14:52:33 2008  Tanaka Akira  <akr@fsij.org>
 	* ext/openssl/ossl_pkey_ec.c (ossl_ec_key_initialize): ditto.
 	  (ossl_ec_group_initialize): ditto.
 
+Wed Dec 31 14:12:35 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* object.c (rb_to_float): replaced by to_flo definition from
+	  math.c  [ruby-dev:37668]
+
+	* math.c (Need_Float): use rb_to_float().
+
 Wed Dec 31 13:49:06 2008  Tanaka Akira  <akr@fsij.org>
 
 	* ext/openssl/lib/openssl/buffering.rb (Buffering#read_nonblock):
diff --git a/math.c b/math.c
index 3ac543150b..63a386360a 100644
--- a/math.c
+++ b/math.c
@@ -15,20 +15,7 @@
 
 VALUE rb_mMath;
 
-static VALUE
-to_flo(VALUE x)
-{
-    if (!rb_obj_is_kind_of(x, rb_cNumeric)) {
-	rb_raise(rb_eTypeError, "can't convert %s into Float",
-		 NIL_P(x) ? "nil" :
-		 x == Qtrue ? "true" :
-		 x == Qfalse ? "false" :
-		 rb_obj_classname(x));
-    }
-    return rb_convert_type(x, T_FLOAT, "Float", "to_f");
-}
-
-#define Need_Float(x) (x) = to_flo(x)
+#define Need_Float(x) (x) = rb_to_float(x)
 #define Need_Float2(x,y) do {\
     Need_Float(x);\
     Need_Float(y);\
diff --git a/object.c b/object.c
index 61aa80a014..aacf7ce43f 100644
--- a/object.c
+++ b/object.c
@@ -2270,19 +2270,15 @@ rb_f_float(VALUE obj, VALUE arg)
 VALUE
 rb_to_float(VALUE val)
 {
-    VALUE v;
-
     if (TYPE(val) == T_FLOAT) return val;
-    if (NIL_P(val)) {
-	rb_raise(rb_eTypeError, "can't convert nil into Float");
+    if (!rb_obj_is_kind_of(val, rb_cNumeric)) {
+	rb_raise(rb_eTypeError, "can't convert %s into Float",
+		 NIL_P(val) ? "nil" :
+		 val == Qtrue ? "true" :
+		 val == Qfalse ? "false" :
+		 rb_obj_classname(val));
     }
-    v = convert_type(val, "Float", "to_f", Qtrue);
-    if (TYPE(v) != T_FLOAT) {
-	const char *cname = rb_obj_classname(val);
-	rb_raise(rb_eTypeError, "can't convert %s to Float (%s#to_f gives %s)",
-		 cname, cname, rb_obj_classname(v));
-    }
-    return v;
+    return rb_convert_type(val, T_FLOAT, "Float", "to_f");
 }
 
 double