diff --git a/ChangeLog b/ChangeLog
index 53184d8099..2d1ae18b46 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Feb  4 08:15:53 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/delegate.rb (Delegator): now inherits BasicObject.
+	  [ruby-dev:39154], [Bug #2679], [ruby-dev:40242]
+
 Thu Feb  4 03:00:59 2010  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* ext/bigdecimal/bigdecimal.c (BigDecimal_DoDivmod): get red of
diff --git a/lib/delegate.rb b/lib/delegate.rb
index b1f79582f4..473fa0cb8f 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -114,11 +114,21 @@
 # subclasses.  Subclasses should redefine \_\_getobj\_\_.  For a concrete
 # implementation, see SimpleDelegator.
 #
-class Delegator
-  [:to_s,:inspect,:=~,:!~,:===,:<=>].each do |m|
-    undef_method m
+class Delegator < BasicObject
+  # :stopdoc:
+  def class
+    (class << self; self; end).superclass
   end
 
+  def extend(*mods)
+    (class << self; self; end).class_eval {include(*mods)}
+  end
+
+  def self.const_missing(n)
+    ::Object.const_get(n)
+  end
+  # :startdoc:
+
   #
   # Pass in the _obj_ to delegate method calls to.  All methods supported by
   # _obj_ will be delegated to.
@@ -131,12 +141,12 @@ class Delegator
   def method_missing(m, *args, &block)
     begin
       target = self.__getobj__
-      unless target.respond_to?(m)
+      unless target.respond_to?(m, true)
         super(m, *args, &block)
       else
         target.__send__(m, *args, &block)
       end
-    rescue Exception
+    rescue ::Exception
       if i = $@.index{|s| %r"\A#{Regexp.quote(__FILE__)}:\d+:in `method_missing'\z"o =~ s}
         $@[0..i] = []
       end
@@ -248,17 +258,6 @@ class SimpleDelegator<Delegator
     raise ArgumentError, "cannot delegate to self" if self.equal?(obj)
     @delegate_sd_obj = obj
   end
-
-  def initialize(obj)   # :nodoc:
-    (self.public_methods - Delegator.public_api).each do |m|
-      class << self
-        self
-      end.class_eval do
-        undef_method m
-      end
-    end
-    super
-  end
 end
 
 # :stopdoc:
diff --git a/test/test_delegate.rb b/test/test_delegate.rb
index bce1231e52..f57263bef0 100644
--- a/test/test_delegate.rb
+++ b/test/test_delegate.rb
@@ -34,12 +34,20 @@ class TestDelegateClass < Test::Unit::TestCase
     def m
       :o
     end
+    private
+    def delegate_test_m
+      :o
+    end
   end
 
   class Foo
     def m
       :m
     end
+    private
+    def delegate_test_m
+      :m
+    end
   end
 
   class Bar < DelegateClass(Foo)
@@ -50,6 +58,9 @@ class TestDelegateClass < Test::Unit::TestCase
     assert_equal(:m, Foo.new.m)
     assert_equal(:m, SimpleDelegator.new(Foo.new).m)
     assert_equal(:m, Bar.new(Foo.new).m)
+    bug = '[ruby-dev:39154]'
+    assert_equal(:m, SimpleDelegator.new(Foo.new).__send__(:delegate_test_m), bug)
+    assert_equal(:m, Bar.new(Foo.new).__send__(:delegate_test_m), bug)
   end
 
   class IV < DelegateClass(Integer)
@@ -67,4 +78,11 @@ class TestDelegateClass < Test::Unit::TestCase
     d = Marshal.load(Marshal.dump(c))
     assert_equal(1, d.var, bug1744)
   end
+
+  def test_copy_frozen
+    bug2679 = '[ruby-dev:40242]'
+    a = [42, :hello].freeze
+    d = SimpleDelegator.new(a)
+    assert_nothing_raised(bug2679) {d.dup[0] += 1}
+  end
 end