diff --git a/lib/bson/ordered_hash.rb b/lib/bson/ordered_hash.rb
index 0a1284c..af82ecc 100644
--- a/lib/bson/ordered_hash.rb
+++ b/lib/bson/ordered_hash.rb
@@ -67,11 +67,10 @@ module BSON
       end
 
       def keys
-        @ordered_keys# || []
+        @ordered_keys.dup
       end
 
       def []=(key, value)
-        #@ordered_keys ||= []
         unless has_key?(key)
           @ordered_keys << key
         end
@@ -79,14 +78,12 @@ module BSON
       end
 
       def each
-        #@ordered_keys ||= []
         @ordered_keys.each { |k| yield k, self[k] }
         self
       end
       alias :each_pair :each
 
       def to_a
-        #@ordered_keys ||= []
         @ordered_keys.map { |k| [k, self[k]] }      
       end
 
@@ -95,7 +92,7 @@ module BSON
       end
 
       def replace(other)
-        @ordered_keys = other.keys
+        @ordered_keys.replace(other.keys)
         super
       end
 
@@ -106,17 +103,15 @@ module BSON
       end
 
       def merge!(other)
-        #@ordered_keys ||= []
         @ordered_keys += other.keys # unordered if not an BSON::OrderedHash
         @ordered_keys.uniq!
         super(other)
       end
 
       alias :update :merge!
-      
+
       def dup
         result = OrderedHash.new
-        #@ordered_keys ||= []
         @ordered_keys.each do |key|
           result[key] = self[key]
         end