diff --git a/lib/mongo.rb b/lib/mongo.rb
index bf4f989..365de1f 100644
--- a/lib/mongo.rb
+++ b/lib/mongo.rb
@@ -18,6 +18,13 @@ require 'mongo/cursor'
 require 'mongo/collection'
 require 'mongo/admin'
 
+begin
+  require 'mongo_ext/cbson'
+    BSON_SERIALIZER = CBson
+  rescue LoadError
+    BSON_SERIALIZER = BSON
+end
+
 module Mongo
   ASCENDING = 1
   DESCENDING = -1
diff --git a/lib/mongo/collection.rb b/lib/mongo/collection.rb
index 7d04b7f..9bfdfe8 100644
--- a/lib/mongo/collection.rb
+++ b/lib/mongo/collection.rb
@@ -221,7 +221,7 @@ module Mongo
       message.put_int(0)
       BSON.serialize_cstr(message, "#{@db.name}.#{@name}")
       message.put_int(0)
-      message.put_array(BSON.new.serialize(selector, false).to_a)
+      message.put_array(BSON_SERIALIZER.serialize(selector, false).unpack("C*"))
       @db.send_message_with_operation(Mongo::Constants::OP_DELETE, message,
         "db.#{@db.name}.remove(#{selector.inspect})")
     end
@@ -258,8 +258,8 @@ module Mongo
       update_options += 1 if options[:upsert]
       update_options += 2 if options[:multi]
       message.put_int(update_options)
-      message.put_array(BSON.new.serialize(selector, false).to_a)
-      message.put_array(BSON.new.serialize(document, false).to_a)
+      message.put_array(BSON_SERIALIZER.serialize(selector, false).unpack("C*"))
+      message.put_array(BSON_SERIALIZER.serialize(document, false).unpack("C*"))
       if options[:safe]
         @db.send_message_with_safe_check(Mongo::Constants::OP_UPDATE, message,
           "db.#{@name}.update(#{selector.inspect}, #{document.inspect})")
@@ -486,7 +486,7 @@ EOS
       message = ByteBuffer.new
       message.put_int(0)
       BSON.serialize_cstr(message, "#{@db.name}.#{collection_name}")
-      documents.each { |doc| message.put_array(BSON.new.serialize(doc, check_keys).to_a) }
+      documents.each { |doc| message.put_array(BSON_SERIALIZER.serialize(doc, check_keys).unpack("C*")) }
       if safe
         @db.send_message_with_safe_check(Mongo::Constants::OP_INSERT, message,
           "db.#{collection_name}.insert(#{documents.inspect})")
diff --git a/lib/mongo/cursor.rb b/lib/mongo/cursor.rb
index 7e49330..86fb64f 100644
--- a/lib/mongo/cursor.rb
+++ b/lib/mongo/cursor.rb
@@ -322,8 +322,8 @@ module Mongo
       if query_contains_special_fields?
         selector = selector_with_special_query_fields
       end
-      message.put_array(BSON.new.serialize(selector).to_a)
-      message.put_array(BSON.new.serialize(@fields).to_a) if @fields
+      message.put_array(BSON_SERIALIZER.serialize(selector, false).unpack("C*"))
+      message.put_array(BSON_SERIALIZER.serialize(@fields, false).unpack("C*")) if @fields
       message
     end
 
diff --git a/lib/mongo/db.rb b/lib/mongo/db.rb
index afdafd5..e6b7521 100644
--- a/lib/mongo/db.rb
+++ b/lib/mongo/db.rb
@@ -450,6 +450,14 @@ module Mongo
       end
     end
 
+    def send_message_with_operation_raw(operation, message, log_message=nil)
+      message_with_headers = add_message_headers_raw(operation, message)
+      @logger.debug("  MONGODB #{log_message || message}") if @logger
+      @semaphore.synchronize do
+        send_message_on_socket(message_with_headers)
+      end
+    end
+
     # Sends a message to the database, waits for a response, and raises
     # and exception if the operation has failed.
     def send_message_with_safe_check(operation, message, log_message=nil)
@@ -641,7 +649,7 @@ module Mongo
       BSON.serialize_cstr(message, "#{@name}.$cmd")
       message.put_int(0)
       message.put_int(-1)
-      message.put_array(BSON.new.serialize({:getlasterror => 1}).to_a)
+      message.put_array(BSON_SERIALIZER.serialize({:getlasterror => 1}, false).unpack("C*"))
       add_message_headers(Mongo::Constants::OP_QUERY, message)
     end
 
@@ -655,7 +663,7 @@ module Mongo
       BSON.serialize_cstr(message, "#{@name}.$cmd")
       message.put_int(0)
       message.put_int(-1)
-      message.put_array(BSON.new.serialize({:reseterror => 1}).to_a)
+      message.put_array(BSON_SERIALIZER.serialize({:reseterror => 1}, false).unpack("C*"))
       add_message_headers(Mongo::Constants::OP_QUERY, message)
     end
 
diff --git a/lib/mongo/util/bson.rb b/lib/mongo/util/bson.rb
index 377951e..d67d950 100644
--- a/lib/mongo/util/bson.rb
+++ b/lib/mongo/util/bson.rb
@@ -71,6 +71,12 @@ class BSON
     @buf.to_a
   end
 
+  # Serializes an object.
+  # Implemented to ensure an API compatible with BSON extension. 
+  def self.serialize(obj, check_keys)
+    new.serialize(obj, check_keys)
+  end
+
   begin
     require 'mongo_ext/cbson'
     def serialize(obj, check_keys=false)
@@ -99,6 +105,12 @@ class BSON
     end
   end
 
+  # Returns the array stored in the buffer.
+  # Implemented to ensure an API compatible with BSON extension. 
+  def unpack(arg)
+    @buf.to_a
+  end
+
   def serialize_key_value(k, v, check_keys)
     k = k.to_s
     if check_keys
diff --git a/lib/mongo/util/byte_buffer.rb b/lib/mongo/util/byte_buffer.rb
index 52bb89a..707702a 100644
--- a/lib/mongo/util/byte_buffer.rb
+++ b/lib/mongo/util/byte_buffer.rb
@@ -20,9 +20,11 @@ class ByteBuffer
   attr_reader :order
 
   def initialize(initial_data=[])
-    @buf = initial_data
+    @buf    = initial_data
     @cursor = 0
-    self.order = :little_endian
+    @order  = :little_endian
+    @int_pack_order    = 'V'
+    @double_pack_order = 'E'
   end
 
   # +endianness+ should be :little_endian or :big_endian. Default is :little_endian