diff --git a/ChangeLog b/ChangeLog
index 9e91ee4784..d96429ecf4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sun Feb 15 03:50:21 2009  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* hash.c (rb_hash): always return a fixnum value because a return
+	  value of rb_hash may be used as a hash value itself and bignums have
+	  no unique VALUE.
+
+	* test/ruby/test_hash.rb: add a test for above.
+
 Sun Feb 15 00:45:41 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* array.c (rb_ary_uniq_bang, rb_ary_uniq): unique by the result of
diff --git a/hash.c b/hash.c
index bfd3fe7f61..5d6b20cea9 100644
--- a/hash.c
+++ b/hash.c
@@ -57,7 +57,19 @@ rb_any_cmp(VALUE a, VALUE b)
 VALUE
 rb_hash(VALUE obj)
 {
-    return rb_funcall(obj, id_hash, 0);
+    VALUE hval = rb_funcall(obj, id_hash, 0);
+  retry:
+    switch (TYPE(hval)) {
+      case T_FIXNUM:
+	return hval;
+
+      case T_BIGNUM:
+	return LONG2FIX(((long*)(RBIGNUM_DIGITS(hval)))[0]);
+
+      default:
+	hval = rb_to_int(hval);
+	goto retry;
+    }
 }
 
 static int
@@ -80,10 +92,7 @@ rb_any_hash(VALUE a)
 	break;
 
       default:
-	hval = rb_funcall(a, id_hash, 0);
-	if (!FIXNUM_P(hval)) {
-	    hval = rb_funcall(hval, '%', 1, INT2FIX(536870923));
-	}
+        hval = rb_hash(a);
 	hnum = (int)FIX2LONG(hval);
     }
     hnum <<= 1;
diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 5a17ac4fb5..50a34b8160 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -849,4 +849,15 @@ class TestHash < Test::Unit::TestCase
   def test_hash_hash
     assert_equal({0=>2,11=>1}.hash, {11=>1,0=>2}.hash)
   end
+
+  def test_hash_bignum_hash
+    x = 2<<(32-3)-1
+    assert_equal({x=>1}.hash, {x=>1}.hash)
+    x = 2<<(64-3)-1
+    assert_equal({x=>1}.hash, {x=>1}.hash)
+
+    o = Object.new
+    def o.hash; 2<<100; end
+    assert_equal({x=>1}.hash, {x=>1}.hash)
+  end
 end