diff --git a/lib/her/model/parse.rb b/lib/her/model/parse.rb
index 061be6fe..1cee7ee1 100644
--- a/lib/her/model/parse.rb
+++ b/lib/her/model/parse.rb
@@ -33,7 +33,7 @@ def parse(data)
         # @private
         def to_params(attributes, changes={})
           filtered_attributes = attributes.dup.symbolize_keys
-          filtered_attributes.merge!(embeded_params(attributes))
+          filtered_attributes.merge!(embedded_params(attributes))
           if her_api.options[:send_only_modified_attributes]
             filtered_attributes = changes.symbolize_keys.keys.inject({}) do |hash, attribute|
               hash[attribute] = filtered_attributes[attribute]
@@ -54,18 +54,34 @@ def to_params(attributes, changes={})
 
 
         # @private
-        # TODO: Handle has_one
-        def embeded_params(attributes)
-          associations[:has_many].select { |a| attributes.include?(a[:data_key])}.compact.inject({}) do |hash, association|
+        def embedded_params(attributes)
+          has_many_params = has_many_embedded_params(attributes)
+          has_one_params  = has_one_embedded_params(attributes)
+          has_many_params.merge(has_one_params)
+        end
+
+        def has_one_embedded_params(attributes)
+          present_has_ones = (associations[:has_one] || []).select { |a| attributes.include?(a[:data_key]) }
+          present_has_ones.compact.each_with_object({}) do |association, hash|
+            params = attributes[association[:data_key]].to_params
+            next if params.empty?
+            klass = her_nearby_class(association[:class_name])
+            hash[association[:data_key]] = klass.include_root_in_json? ? params[klass.root_element] : params
+          end
+        end
+
+        def has_many_embedded_params(attributes)
+          present_has_many = (associations[:has_many] || []).select { |a| attributes.include?(a[:data_key]) }
+          present_has_many.compact.each_with_object({}) do |association, hash|
             params = attributes[association[:data_key]].map(&:to_params)
             next if params.empty?
-            if association[:class_name].constantize.include_root_in_json?
-              root = association[:class_name].constantize.root_element
+            klass = her_nearby_class(association[:class_name])
+            if klass.include_root_in_json?
+              root = klass.root_element
               hash[association[:data_key]] = params.map { |n| n[root] }
             else
               hash[association[:data_key]] = params
             end
-            hash
           end
         end
 
diff --git a/spec/model/associations_spec.rb b/spec/model/associations_spec.rb
index fc952721..7dcadd12 100644
--- a/spec/model/associations_spec.rb
+++ b/spec/model/associations_spec.rb
@@ -251,6 +251,12 @@
       params[:comments].length.should eq(2)
     end
 
+    it 'includes has_one relationships in params by default' do
+      params = @user_with_included_data.to_params
+      params[:role].should be_kind_of(Hash)
+      params[:role][:body].should eq("Admin")
+    end
+
     [:create, :save_existing, :destroy].each do |type|
       context "after #{type}" do
         let(:subject) { self.send("user_with_included_data_after_#{type}")}