diff --git a/lib/mongo/types/objectid.rb b/lib/mongo/types/objectid.rb
index d4ebb61..ec46b8b 100644
--- a/lib/mongo/types/objectid.rb
+++ b/lib/mongo/types/objectid.rb
@@ -15,6 +15,8 @@
 # ++
 
 require 'mutex_m'
+require 'socket'
+require 'digest/md5'
 require 'mongo/util/byte_buffer'
 
 module Mongo
@@ -41,10 +43,6 @@ module Mongo
   #   10
   #   11
   class ObjectID
-
-    MACHINE = ( val = rand(0x1000000); [val & 0xff, (val >> 8) & 0xff, (val >> 16) & 0xff] )
-    PID = ( val = rand(0x10000); [val & 0xff, (val >> 8) & 0xff]; )
-
     # The string representation of an OID is different than its internal
     # and BSON byte representations. The BYTE_ORDER here maps
     # internal/BSON byte position (the index in BYTE_ORDER) to the
@@ -56,7 +54,6 @@ module Mongo
     LOCK = Object.new
     LOCK.extend Mutex_m
 
-    @@index_time = Time.new.to_i
     @@index = 0
 
     # Given a string representation of an ObjectID, return a new ObjectID
@@ -78,9 +75,8 @@ module Mongo
     end
 
     # +data+ is an array of bytes. If nil, a new id will be generated.
-    # The time +t+ is only used for testing; leave it nil.
-    def initialize(data=nil, t=nil)
-      @data = data || generate_id(t)
+    def initialize(data=nil)
+      @data = data || generate
     end
 
     def eql?(other)
@@ -100,34 +96,39 @@ module Mongo
       str
     end
 
-    # (Would normally be private, but isn't so we can test it.)
-    def generate_id(t=nil)
-      t ||= Time.new.to_i
+    private
+
+    def generate
+      # 4 bytes current time
+      time = Time.new.to_i
       buf = ByteBuffer.new
-      buf.put_int(t & 0xffffffff)
-      buf.put_array(MACHINE)
-      buf.put_array(PID)
-      i = index_for_time(t)
-      buf.put(i & 0xff)
-      buf.put((i >> 8) & 0xff)
-      buf.put((i >> 16) & 0xff)
+      buf.put_int(time & 0xFFFFFFFF)
+
+      # 3 bytes machine
+      machine_hash = Digest::MD5.digest(Socket.gethostname)
+      buf.put(machine_hash[0])
+      buf.put(machine_hash[1])
+      buf.put(machine_hash[2])
+
+      # 2 bytes pid
+      pid = Process.pid % 0xFFFF
+      buf.put(pid & 0xFF)
+      buf.put((pid >> 8) & 0xFF)
+
+      # 3 bytes inc
+      inc = get_inc
+      buf.put(inc & 0xFF)
+      buf.put((inc >> 8) & 0xFF)
+      buf.put((inc >> 16) & 0xFF)
 
       buf.rewind
       buf.to_a.dup
     end
 
-    # (Would normally be private, but isn't so we can test it.)
-    def index_for_time(t)
+    def get_inc
       LOCK.mu_synchronize {
-        if t != @@index_time
-          @@index = 0
-          @@index_time = t
-        end
-        retval = @@index
-        @@index += 1
-        retval
+        @@index = (@@index + 1) % 0xFFFFFF
       }
     end
-
   end
 end
diff --git a/test/test_objectid.rb b/test/test_objectid.rb
index 2daf08c..b41c8f5 100644
--- a/test/test_objectid.rb
+++ b/test/test_objectid.rb
@@ -7,41 +7,19 @@ class ObjectIDTest < Test::Unit::TestCase
   include Mongo
 
   def setup
-    @t = 42
-    @o = ObjectID.new(nil, @t)
-  end
-
-  def test_index_for_time
-    t = 99
-    assert_equal 0, @o.index_for_time(t)
-    assert_equal 1, @o.index_for_time(t)
-    assert_equal 2, @o.index_for_time(t)
-    t = 100
-    assert_equal 0, @o.index_for_time(t)
-  end
-
-  def test_time_bytes
-    a = @o.to_a
-    assert_equal @t, a[0]
-    3.times { |i| assert_equal 0, a[i+1] }
-
-    t = 43
-    o = ObjectID.new(nil, t)
-    a = o.to_a
-    assert_equal t, a[0]
-    3.times { |i| assert_equal 0, a[i+1] }
-    assert_equal 1, o.index_for_time(t) # 0 was used for o
+    @o = ObjectID.new()
   end
 
   def test_different
-    o2 = ObjectID.new(nil, @t)
-    assert @o.to_a != o2.to_a
+    a = ObjectID.new
+    b = ObjectID.new
+    assert_not_equal a.to_a, b.to_a
+    assert_not_equal a, b
   end
 
   def test_eql?
     o2 = ObjectID.new(@o.to_a)
-    assert @o.eql?(o2)
-    assert @o == o2
+    assert_equal @o, o2
   end
 
   def test_to_s