diff --git a/app/helpers/quantities_helper.rb b/app/helpers/quantities_helper.rb
index fe34c7f..89c9934 100644
--- a/app/helpers/quantities_helper.rb
+++ b/app/helpers/quantities_helper.rb
@@ -6,8 +6,8 @@ module QuantitiesHelper
     end
   end
 
-  def parent_options
-    options = nested_set_options(@quantities, @quantity) do |i|
+  def parent_options(domain)
+    options = nested_set_options(@quantities.send(domain), @quantity) do |i|
       raw("#{' ' * i.level}#{i.name}")
     end
     options.unshift([t('.null_parent'), nil])
diff --git a/app/views/quantities/_form.html.erb b/app/views/quantities/_form.html.erb
index 33cf33c..ebe892c 100644
--- a/app/views/quantities/_form.html.erb
+++ b/app/views/quantities/_form.html.erb
@@ -2,9 +2,25 @@
 
 <div class="box tabular">
   <p><%= f.select :domain, domain_options, required: true %></p>
-  <p>
-    <%= f.select :parent_id, parent_options, required: true, label: :field_parent_quantity %>
-  </p>
+  <% Quantity.domains.each_key do |d| %>
+    <div id="parent_select_<%= d %>" style="display: none">
+      <p><%= f.select :parent_id, parent_options(d),
+        {required: true, label: :field_parent_quantity} %></p>
+    </div>
+  <% end %>
   <p><%= f.text_field :name, size: 25, required: true %></p>
   <p><%= f.text_field :description, size: 200 %></p>
 </div>
+
+<%= javascript_tag do %>
+  function domainChange() {
+    $('[id^=parent_select_]').prop('disabled', true).hide();
+    $('[id=parent_select_'+$('#quantity_domain option:selected').val()+']')
+      .prop('disabled', false).show();
+  }
+  $('#quantity-form').on('click', '#quantity_domain', domainChange);
+
+  $(document).ready(function() {
+    domainChange();
+  });
+<% end %>