diff --git a/app/controllers/api/v1/registrant/registry_locks_controller.rb b/app/controllers/api/v1/registrant/registry_locks_controller.rb
index 27c98cc9f..5100cd748 100644
--- a/app/controllers/api/v1/registrant/registry_locks_controller.rb
+++ b/app/controllers/api/v1/registrant/registry_locks_controller.rb
@@ -1,3 +1,5 @@
+require 'serializers/registrant_api/domain'
+
 module Api
   module V1
     module Registrant
@@ -7,7 +9,8 @@ module Api
 
         def create
           if @domain.apply_registry_lock
-            render json: @domain
+            serializer = Serializers::RegistrantApi::Domain.new(@domain)
+            render json: serializer.to_json
           else
             render json: { errors: [{ base: ['Domain cannot be locked'] }] },
                    status: :unprocessable_entity
@@ -16,7 +19,8 @@ module Api
 
         def destroy
           if @domain.remove_registry_lock
-            render json: @domain
+            serializer = Serializers::RegistrantApi::Domain.new(@domain)
+            render json: serializer.to_json
           else
             render json: { errors: [{ base: ['Domain is not locked'] }] },
                    status: :unprocessable_entity
diff --git a/doc/registrant-api/v1/domain.md b/doc/registrant-api/v1/domain.md
index f56bb6014..5c309ce15 100644
--- a/doc/registrant-api/v1/domain.md
+++ b/doc/registrant-api/v1/domain.md
@@ -23,7 +23,7 @@ Content-Type: application/json
       "id": "98d1083a-8863-4153-93e4-caee4a013535",
       "name": "domain0.ee",
       "registrar": "Best Names",
-      "valid_from": "2015-09-09T09:11:14.861Z",
+      "registered_at": "2015-09-09T09:11:14.861Z",
       "valid_to": "2016-09-09T09:11:14.861Z",
       "registrant_id": 1,
       "transfer_code": "98oiewslkfkd",
@@ -89,6 +89,7 @@ Content-Type: application/json
       "name": "domain0.ee",
       "registrar": "Best Names",
       "valid_to": "2016-09-09T09:11:14.861Z",
+      "registered_at": "2015-09-09T09:11:14.861Z",
       "registrant_id": 1,
       "transfer_code": "98oiewslkfkd",
       "created_at": "2015-09-09T09:11:14.861Z",
diff --git a/doc/registrant-api/v1/registry_lock.md b/doc/registrant-api/v1/registry_lock.md
index b8d440554..849b27db5 100644
--- a/doc/registrant-api/v1/registry_lock.md
+++ b/doc/registrant-api/v1/registry_lock.md
@@ -19,12 +19,10 @@ HTTP/1.1 200
 Content-Type: application/json
 
 {
-  "uuid": "98d1083a-8863-4153-93e4-caee4a013535",
+  "id": "98d1083a-8863-4153-93e4-caee4a013535",
   "name": "domain0.ee",
-  "registrar_id": 2,
+  "registrar": "Best Names",
   "registered_at": "2015-09-09T09:11:14.861Z",
-  "status": null,
-  "valid_from": "2015-09-09T09:11:14.861Z",
   "valid_to": "2016-09-09T09:11:14.861Z",
   "registrant_id": 1,
   "transfer_code": "98oiewslkfkd",
@@ -43,6 +41,7 @@ Content-Type: application/json
   "delete_at": "2016-10-24T09:11:14.861Z",
   "registrant_verification_asked_at": null,
   "registrant_verification_token": null,
+  "locked_by_registrant_at": "2015-09-09T09:11:14.861Z",
   "pending_json": {},
   "force_delete_at": null,
   "statuses": [
@@ -113,12 +112,10 @@ HTTP/1.1 200
 Content-Type: application/json
 
 {
-  "uuid": "98d1083a-8863-4153-93e4-caee4a013535",
+  "id": "98d1083a-8863-4153-93e4-caee4a013535",
   "name": "domain0.ee",
-  "registrar_id": 2,
+  "registrar": "Best Names",
   "registered_at": "2015-09-09T09:11:14.861Z",
-  "status": null,
-  "valid_from": "2015-09-09T09:11:14.861Z",
   "valid_to": "2016-09-09T09:11:14.861Z",
   "registrant_id": 1,
   "transfer_code": "98oiewslkfkd",
@@ -137,6 +134,7 @@ Content-Type: application/json
   "delete_at": "2016-10-24T09:11:14.861Z",
   "registrant_verification_asked_at": null,
   "registrant_verification_token": null,
+  "locked_by_registrant_at": null,
   "pending_json": {},
   "force_delete_at": null,
   "statuses": [
diff --git a/test/integration/api/registrant/registrant_api_registry_locks_test.rb b/test/integration/api/registrant/registrant_api_registry_locks_test.rb
index bb50bdc1b..846bcb8e5 100644
--- a/test/integration/api/registrant/registrant_api_registry_locks_test.rb
+++ b/test/integration/api/registrant/registrant_api_registry_locks_test.rb
@@ -77,6 +77,7 @@ class RegistrantApiRegistryLocksTest < ApplicationIntegrationTest
 
     response_json = JSON.parse(response.body, symbolize_names: true)
     assert(response_json[:statuses].include?(DomainStatus::OK))
+    refute(response_json[:locked_by_registrant_at])
     @domain.reload
     refute(@domain.locked_by_registrant?)
   end
@@ -121,6 +122,19 @@ class RegistrantApiRegistryLocksTest < ApplicationIntegrationTest
     assert(response_json[:statuses].include?(DomainStatus::SERVER_UPDATE_PROHIBITED))
   end
 
+  def test_locking_domains_returns_serialized_domain_object
+    post '/api/v1/registrant/domains/1b3ee442-e8fe-4922-9492-8fcb9dccc69c/registry_lock',
+         {}, @auth_headers
+
+    assert_equal(200, response.status)
+    response_json = JSON.parse(response.body, symbolize_names: true)
+
+    assert_equal('Best Names', response_json[:registrar])
+    assert_equal(['ns1.bestnames.test', 'ns2.bestnames.test'].to_set,
+                 response_json[:nameservers].to_set)
+    assert_equal(Time.zone.parse('2010-07-05'), response_json[:locked_by_registrant_at])
+  end
+
   private
 
   def auth_token
diff --git a/test/lib/serializers/registrant_api/domain_test.rb b/test/lib/serializers/registrant_api/domain_test.rb
index 74facf87c..6a9b552d1 100644
--- a/test/lib/serializers/registrant_api/domain_test.rb
+++ b/test/lib/serializers/registrant_api/domain_test.rb
@@ -47,8 +47,6 @@ class SerializersRegistrantApiDomainTest < ApplicationIntegrationTest
               registrant_verification_token pending_json force_delete_at statuses
               locked_by_registrant_at reserved status_notes nameservers]
 
-    pp @json
-
     assert_equal(keys, @json.keys & keys)
   end
 end