diff --git a/ChangeLog b/ChangeLog
index a9032efddc..024ee25ca7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Jul 12 23:30:26 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* object.c (rb_to_integer, rb_check_to_integer): return Bignum
+	  as-is.
+
 Sun Jul 12 21:07:46 2009  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* complex.c: use k_exact_{zero,one}_p macro.
diff --git a/object.c b/object.c
index 2df7239f18..d86c6e49d4 100644
--- a/object.c
+++ b/object.c
@@ -2057,6 +2057,7 @@ rb_to_integer(VALUE val, const char *method)
     VALUE v;
 
     if (FIXNUM_P(val)) return val;
+    if (TYPE(val) == T_BIGNUM) return val;
     v = convert_type(val, "Integer", method, Qtrue);
     if (!rb_obj_is_kind_of(v, rb_cInteger)) {
 	const char *cname = rb_obj_classname(val);
@@ -2072,6 +2073,7 @@ rb_check_to_integer(VALUE val, const char *method)
     VALUE v;
 
     if (FIXNUM_P(val)) return val;
+    if (TYPE(val) == T_BIGNUM) return val;
     v = convert_type(val, "Integer", method, Qfalse);
     if (!rb_obj_is_kind_of(v, rb_cInteger)) {
 	return Qnil;