diff --git a/app/helpers/domains_helper.rb b/app/helpers/domains_helper.rb
index 89db2fb..7c69184 100644
--- a/app/helpers/domains_helper.rb
+++ b/app/helpers/domains_helper.rb
@@ -1,25 +1,30 @@
 module DomainsHelper
 
   # Human names for domain states
   def human_state(state)
     human = case state.to_sym
             when :initial then 'Initial'
             when :pending_install then 'Becoming public'
             when :pending_signing then 'Signing zone'
             when :wait_for_ready then 'Waiting for KSK to become ready'
             when :pending_ds then 'Publishing DS records'
             when :pending_ds_rollover then 'Performing KSK rollover'
             when :pending_plain then 'Removing dnssec'
             when :pending_remove then 'Preparing removal'
             when :operational then 'Operational'
             when :destroy then 'Ready to be destroyed'
             else
               state
             end
 
     prog = Domain.dnssec_progress(state)
     return human if prog.nil?
 
     "#{human} (#{prog})"
   end
+
+  # Most of the time the parent zone will be easily computed
+  def guess_parent_zone(name)
+    name.split('.', 2).last || ''
+  end
 end
diff --git a/app/views/domains/_dnssec_form.html.erb b/app/views/domains/_dnssec_form.html.erb
index 03270ce..52f4624 100644
--- a/app/views/domains/_dnssec_form.html.erb
+++ b/app/views/domains/_dnssec_form.html.erb
@@ -1,13 +1,13 @@
 <%= bootstrap_form_for(@domain, layout: :horizontal, label_col: 'col-sm-2', control_col: 'col-sm-4') do |f| %>
   <%= f.hidden_field :group_id %>
   <%= f.static_control :name %>
   <%= f.select :dnssec, [['Enable', true], ['Disable', false]] %>
 
   <fieldset id="dnssec_fieldset" <%= 'disabled' if !@domain.dnssec %>>
     <%= f.collection_select :dnssec_policy_id, DnssecPolicy.all, :id, :name %>
     <%= f.select :dnssec_parent_authority, Domain.dnssec_parent_authorities, include_blank: true,
     label: 'Parent authority', help: 'WebDNS will manage DS records automatically, handling initial setup and key rollovers.' %>
-    <%= f.text_field :dnssec_parent, label: 'Parent zone', help: 'The parent zone to publish the DS records.' %>
+    <%= f.text_field :dnssec_parent, value: guess_parent_zone(@domain.name), label: 'Parent zone', help: 'The parent zone to publish the DS records.' %>
   </fieldset>
     <%= f.submit 'Save', class: 'btn btn-primary col-sm-offset-2' %>
 <% end %>