diff --git a/app/controllers/api/v1/registrant/registry_locks_controller.rb b/app/controllers/api/v1/registrant/registry_locks_controller.rb
index b01e6b40d..57a0bfd0c 100644
--- a/app/controllers/api/v1/registrant/registry_locks_controller.rb
+++ b/app/controllers/api/v1/registrant/registry_locks_controller.rb
@@ -17,7 +17,7 @@ module Api
           if @domain.remove_registry_lock
             render json: @domain
           else
-            render json: { errors: [{ base: ['Domain not locked'] }] },
+            render json: { errors: [{ base: ['Domain is not locked'] }] },
                    status: :unprocessable_entity
           end
         end
diff --git a/doc/registrant-api/v1/domain_lock.md b/doc/registrant-api/v1/domain_lock.md
index 5f275edb4..7e24e2827 100644
--- a/doc/registrant-api/v1/domain_lock.md
+++ b/doc/registrant-api/v1/domain_lock.md
@@ -139,12 +139,12 @@ Content-Type: application/json
 #### Response for failure
 
 ```
-HTTP/1.1 400
+HTTP/1.1 422
 Content-Type: application/json
 
 {
   "errors": [
-    { "base": "domain cannot be unlocked" }
+    { "base": "Domain is not locked" }
   ]
 }
 
diff --git a/test/integration/api/registrant/registrant_api_domain_registry_lock_test.rb b/test/integration/api/registrant/registrant_api_domain_registry_lock_test.rb
index 8ad1d0826..1548c5d13 100644
--- a/test/integration/api/registrant/registrant_api_domain_registry_lock_test.rb
+++ b/test/integration/api/registrant/registrant_api_domain_registry_lock_test.rb
@@ -85,7 +85,7 @@ class RegistrantApiDomainRegistryLockTest < ApplicationIntegrationTest
 
     response_json = JSON.parse(response.body, symbolize_names: true)
     assert_equal(422, response.status)
-    assert_equal({ errors: [{ base: ['Domain not locked'] }] }, response_json)
+    assert_equal({ errors: [{ base: ['Domain is not locked'] }] }, response_json)
   end
 
   def test_returns_404_when_domain_is_not_found