diff --git a/lib/mongo/collection.rb b/lib/mongo/collection.rb
index e0a5d20..ffa3474 100644
--- a/lib/mongo/collection.rb
+++ b/lib/mongo/collection.rb
@@ -241,11 +241,11 @@ module Mongo
     # @example remove only documents that have expired:
     #   users.remove({:expire => {"$lte" => Time.now}})
     def remove(selector={})
-      message = ByteBuffer.new
-      message.put_int(0)
+      # Initial byte is 0.
+      message = ByteBuffer.new([0, 0, 0, 0])
       BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@name}")
       message.put_int(0)
-      message.put_array(BSON.serialize(selector, false).unpack("C*"))
+      message.put_array(BSON.serialize(selector, false).to_a)
       @connection.send_message(Mongo::Constants::OP_DELETE, message,
         "db.#{@db.name}.remove(#{selector.inspect})")
     end
@@ -269,15 +269,15 @@ module Mongo
     #   will be raised on an error. Note that a safe check requires an extra
     #   round-trip to the database.
     def update(selector, document, options={})
-      message = ByteBuffer.new
-      message.put_int(0)
+      # Initial byte is 0.
+      message = ByteBuffer.new([0, 0, 0, 0])
       BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@name}")
       update_options  = 0
       update_options += 1 if options[:upsert]
       update_options += 2 if options[:multi]
       message.put_int(update_options)
-      message.put_array(BSON.serialize(selector, false).unpack("C*"))
-      message.put_array(BSON.serialize(document, false).unpack("C*"))
+      message.put_array(BSON.serialize(selector, false).to_a)
+      message.put_array(BSON.serialize(document, false).to_a)
       if options[:safe]
         @connection.send_message_with_safe_check(Mongo::Constants::OP_UPDATE, message, @db.name,
           "db.#{@name}.update(#{selector.inspect}, #{document.inspect})")
@@ -589,10 +589,10 @@ EOS
     # Takes an array of +documents+, an optional +collection_name+, and a
     # +check_keys+ setting.
     def insert_documents(documents, collection_name=@name, check_keys=true, safe=false)
-      message = ByteBuffer.new
-      message.put_int(0)
+      # Initial byte is 0.
+      message = ByteBuffer.new([0, 0, 0, 0])
       BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{collection_name}")
-      documents.each { |doc| message.put_array(BSON.serialize(doc, check_keys).unpack("C*")) }
+      documents.each { |doc| message.put_array(BSON.serialize(doc, check_keys).to_a) }
       if safe
         @connection.send_message_with_safe_check(Mongo::Constants::OP_INSERT, message, @db.name,
           "db.#{collection_name}.insert(#{documents.inspect})")
diff --git a/lib/mongo/cursor.rb b/lib/mongo/cursor.rb
index 7be53ac..5663692 100644
--- a/lib/mongo/cursor.rb
+++ b/lib/mongo/cursor.rb
@@ -220,8 +220,7 @@ module Mongo
     # @return [True]
     def close
       if @cursor_id
-        message = ByteBuffer.new
-        message.put_int(0)
+        message = ByteBuffer.new([0, 0, 0, 0])
         message.put_int(1)
         message.put_long(@cursor_id)
         @connection.send_message(Mongo::Constants::OP_KILL_CURSORS, message, "cursor.close()")
@@ -315,9 +314,7 @@ module Mongo
 
     def refill_via_get_more
       return if send_initial_query || @cursor_id.zero?
-      message = ByteBuffer.new
-      # Reserved.
-      message.put_int(0)
+      message = ByteBuffer.new([0, 0, 0, 0])
 
       # DB name.
       db_name = @admin ? 'admin' : @db.name
@@ -359,8 +356,8 @@ module Mongo
       if query_contains_special_fields?
         selector = selector_with_special_query_fields
       end
-      message.put_array(BSON.serialize(selector, false).unpack("C*"))
-      message.put_array(BSON.serialize(@fields, false).unpack("C*")) if @fields
+      message.put_array(BSON.serialize(selector, false).to_a)
+      message.put_array(BSON.serialize(@fields, false).to_a) if @fields
       message
     end
 
diff --git a/lib/mongo/util/byte_buffer.rb b/lib/mongo/util/byte_buffer.rb
index eea9b09..678d738 100644
--- a/lib/mongo/util/byte_buffer.rb
+++ b/lib/mongo/util/byte_buffer.rb
@@ -17,6 +17,20 @@
 # A byte buffer.
 class ByteBuffer
 
+  # Commonly-used integers.
+  INT_LOOKUP = {
+    0    => [0, 0, 0, 0],
+    1    => [1, 0, 0, 0],
+    2    => [2, 0, 0, 0],
+    3    => [3, 0, 0, 0],
+    4    => [4, 0, 0, 0],
+    2001 => [209, 7, 0, 0],
+    2002 => [210, 7, 0, 0],
+    2004 => [212, 7, 0, 0],
+    2005 => [213, 7, 0, 0],
+    2006 => [214, 7, 0, 0]
+  }
+
   attr_reader :order
 
   def initialize(initial_data=[])
@@ -100,8 +114,10 @@ class ByteBuffer
   end
 
   def put_int(i, offset=nil)
-    a = []
-    [i].pack(@int_pack_order).each_byte { |b| a << b }
+    unless a = INT_LOOKUP[i]
+      a = []
+      [i].pack(@int_pack_order).each_byte { |b| a << b }
+    end
     put_array(a, offset)
   end