diff --git a/ChangeLog b/ChangeLog
index a244e1c625..0af30b4672 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Thu Jun 18 01:35:51 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* numeric.c (flo_cmp): Infinity is greater than any bignum
+	  number.  [ruby-dev:38672]
+
+	* bignum.c (rb_big_cmp): ditto.
+
 Thu Jun 18 01:29:16 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* file.c (file_expand_path): drive letter is ascii only.
diff --git a/bignum.c b/bignum.c
index cba4210946..bb6430c19d 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1280,7 +1280,15 @@ rb_big_cmp(VALUE x, VALUE y)
 	break;
 
       case T_FLOAT:
-	return rb_dbl_cmp(rb_big2dbl(x), RFLOAT_VALUE(y));
+	{
+	    double a = RFLOAT_VALUE(y);
+
+	    if (isinf(a)) {
+		if (a > 0.0) return INT2FIX(-1);
+		else return INT2FIX(1);
+	    }
+	    return rb_dbl_cmp(rb_big2dbl(x), a);
+	}
 
       default:
 	return rb_num_coerce_cmp(x, y, rb_intern("<=>"));
diff --git a/numeric.c b/numeric.c
index a4ccd01b5b..74061fc690 100644
--- a/numeric.c
+++ b/numeric.c
@@ -943,6 +943,10 @@ flo_cmp(VALUE x, VALUE y)
 	break;
 
       case T_BIGNUM:
+	if (isinf(a)) {
+	    if (a > 0.0) return INT2FIX(1);
+	    else return INT2FIX(-1);
+	}
 	b = rb_big2dbl(y);
 	break;
 
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index 96fd354aba..15e17ad92a 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -215,6 +215,11 @@ class TestFloat < Test::Unit::TestCase
 
     assert_equal(-1, 1.0 <=> 2**32)
 
+    assert_equal(1, inf <=> (Float::MAX.to_i*2))
+    assert_equal(-1, -inf <=> (-Float::MAX.to_i*2))
+    assert_equal(-1, (Float::MAX.to_i*2) <=> inf)
+    assert_equal(1, (-Float::MAX.to_i*2) <=> -inf)
+
     assert_raise(ArgumentError) { 1.0 > nil }
     assert_raise(ArgumentError) { 1.0 >= nil }
     assert_raise(ArgumentError) { 1.0 < nil }