diff --git a/lib/tempfile.rb b/lib/tempfile.rb
index 9f4ed8f..8dbe53d 100644
--- a/lib/tempfile.rb
+++ b/lib/tempfile.rb
@@ -4,7 +4,6 @@
 # $Id$
 #
 
-require 'delegate'
 require 'tmpdir'
 require 'thread'
 
@@ -78,9 +77,11 @@ require 'thread'
 # Tempfile itself however may not be entirely thread-safe. If you access the
 # same Tempfile object from multiple threads then you should protect it with a
 # mutex.
-class Tempfile < DelegateClass(File)
+class Tempfile < File
   include Dir::Tmpname
 
+  @@tmpmap = {}
+
   # call-seq:
   #    new(basename, [tmpdir = Dir.tmpdir], [options])
   #
@@ -143,33 +144,26 @@ class Tempfile < DelegateClass(File)
       else
         opts = perm
       end
-      @data[1] = @tmpfile = File.open(tmpname, mode, opts)
+      @data[1] = @tmpfile = super(tmpname, mode, opts)
       @data[0] = @tmpname = tmpname
       @mode = mode & ~(File::CREAT|File::EXCL)
       perm or opts.freeze
       @opts = opts
     end
+    @@tmpmap[@tmpname] = 1
+    @data[2] = @@tmpmap
+  end
 
-    super(@tmpfile)
+  def dup
+    @@tmpmap[@tmpname] += 1
+    super
   end
 
   # Opens or reopens the file with mode "r+".
   def open
-    @tmpfile.close if @tmpfile
-    @tmpfile = File.open(@tmpname, @mode, @opts)
-    @data[1] = @tmpfile
-    __setobj__(@tmpfile)
-  end
-
-  def _close    # :nodoc:
-    begin
-      @tmpfile.close if @tmpfile
-    ensure
-      @tmpfile = nil
-      @data[1] = nil if @data
-    end
+    opts = @opts.is_a?(Hash) ? @opts : nil
+    @tmpfile = reopen(@tmpname, @mode, opts)
   end
-  protected :_close
 
   # Closes the file. If +unlink_now+ is true, then the file will be unlinked
   # (deleted) after closing. Of course, you can choose to later call #unlink
@@ -178,19 +172,23 @@ class Tempfile < DelegateClass(File)
   # If you don't explicitly unlink the temporary file, the removal
   # will be delayed until the object is finalized.
   def close(unlink_now=false)
+    begin
+      super() if @tmpfile
+    ensure
+      @tmpfile = nil
+      @data[1] = nil if @data
+    end
     if unlink_now
-      close!
-    else
-      _close
+      unlink
+      ObjectSpace.undefine_finalizer(self)
     end
+    nil
   end
 
   # Closes and unlinks (deletes) the file. Has the same effect as called
   # <tt>close(true)</tt>.
   def close!
-    _close
-    unlink
-    ObjectSpace.undefine_finalizer(self)
+    close(true)
   end
 
   # Unlinks (deletes) the file from the filesystem. One should always unlink
@@ -271,13 +269,13 @@ class Tempfile < DelegateClass(File)
     def call(*args)
       return if @pid != $$
 
-      path, tmpfile = *@data
+      path, tmpfile, tmpmap = *@data
 
       STDERR.print "removing ", path, "..." if $DEBUG
 
       tmpfile.close if tmpfile
 
-      if path
+      if path && tmpmap.has_key?(path) && (tmpmap[path] -= 1) == 0
         begin
           File.unlink(path)
         rescue Errno::ENOENT
@@ -285,6 +283,9 @@ class Tempfile < DelegateClass(File)
       end
 
       STDERR.print "done\n" if $DEBUG
+
+    ensure
+      tmpmap.delete(path)
     end
   end
   # :startdoc:
diff --git a/test/test_tempfile.rb b/test/test_tempfile.rb
index 1462a98..b7cf77e 100644
--- a/test/test_tempfile.rb
+++ b/test/test_tempfile.rb
@@ -304,5 +304,19 @@ puts Tempfile.new('foo').path
       assert_equal(0600, t.stat.mode & 0777)
     end
   end
-end
 
+  def test_dup
+    t = tempfile("foo")
+    t_dup = t.dup
+    assert(t_dup.is_a?(File))
+  end
+
+  def test_duped_finalizer
+    t = Tempfile.new("foo")
+    path = t.path
+    t_dup = t.dup
+    t = nil
+    GC.start
+    assert(File.exist?(path))
+  end
+end