gistfile1

diff --git a/lib/cassandra_object/identity/natural_key_factory.rb b/lib/cassandra_object/identity/natural_key_factory.rb
index 69dec5b..91859ee 100644
--- a/lib/cassandra_object/identity/natural_key_factory.rb
+++ b/lib/cassandra_object/identity/natural_key_factory.rb
@@ -35,7 +35,7 @@ module CassandraObject
       end
 
       def next_key(object)
-        NaturalKey.new(attributes.map { |a| object[a.to_s] }.join(separator))
+        NaturalKey.new(attributes.map { |a| object.attributes[a.to_s] }.join(separator))
       end
 
       def parse(paramized_key)
diff --git a/lib/cassandra_object/persistence.rb b/lib/cassandra_object/persistence.rb
index aec6e7e..6bd2006 100644
--- a/lib/cassandra_object/persistence.rb
+++ b/lib/cassandra_object/persistence.rb
@@ -52,7 +52,7 @@ module CassandraObject
       end
 
       def write(key, attributes, schema_version)
-        returning(key || next_key(attributes)) do |key|
+        returning(key) do |key|
           connection.insert(column_family, key.to_s, encode_columns_hash(attributes, schema_version))
         end
       end
@@ -88,8 +88,8 @@ module CassandraObject
         run_callbacks :before_save
 
         changed_attributes = changed.inject({}) { |h, n| h[n] = read_attribute(n); h }
-        returned_key = self.class.write(key, changed_attributes, schema_version)
-        @key ||= returned_key
+        @key ||= self.class.next_key(self)
+        self.class.write(key, changed_attributes, schema_version)
         run_callbacks :after_save
         run_callbacks :after_create if was_new_record
         @new_record = false
diff --git a/test/fixture_models.rb b/test/fixture_models.rb
index fb63127..f01fe2e 100644
--- a/test/fixture_models.rb
+++ b/test/fixture_models.rb
@@ -52,3 +52,8 @@ class Payment < CassandraObject::Base
 end
 
 MockRecord = Struct.new(:key)
+
+class Person < CassandraObject::Base
+  attribute :name, :type => String
+  attribute :age,  :type => Integer
+end
diff --git a/test/identity/natural_key_factory_test.rb b/test/identity/natural_key_factory_test.rb
index 0ef115d..9275ffa 100644
--- a/test/identity/natural_key_factory_test.rb
+++ b/test/identity/natural_key_factory_test.rb
@@ -5,10 +5,11 @@ module Identity
     context "With one attribute" do
       setup do
         @key_factory = CassandraObject::Identity::NaturalKeyFactory.new :attributes => :name
+        @james = Person.new("name" => "james")
       end
 
       should "have a key whose string and param value is the value of that attribute" do
-        @key = @key_factory.next_key({"name" => "james"})
+        @key = @key_factory.next_key(@james)
 
         assert_equal "james", @key.to_s
         assert_equal "james", @key.to_param
@@ -32,10 +33,11 @@ module Identity
     context "With multiple attributes" do
       setup do
         @key_factory = CassandraObject::Identity::NaturalKeyFactory.new :attributes => [:name, :age]
+        @james = Person.new("name" => "james", "age" => 23)
       end
 
       should "create a key whose string value is the two values, joined with a separator" do
-        key = @key_factory.next_key({"name" => "james", "age" => 23})
+        key = @key_factory.next_key(@james)
         
         assert_equal "james-23", key.to_s
         assert_equal "james-23", key.to_param
@@ -60,10 +62,11 @@ module Identity
       setup do
         @key_factory = CassandraObject::Identity::NaturalKeyFactory.new :attributes => [:name, :age],
                                                                         :separator  => "#"
+        @james = Person.new("name" => "james", "age" => 23)
       end
 
       should "join the attributes with the custom separator" do
-        key = @key_factory.next_key({"name" => "james", "age" => 23})
+        key = @key_factory.next_key(@james)
 
         assert_equal "james#23", key.to_s
       end