diff --git a/app/api/repp/domain_contacts_v1.rb b/app/api/repp/domain_contacts_v1.rb
index a5f337139..7f3e323ac 100644
--- a/app/api/repp/domain_contacts_v1.rb
+++ b/app/api/repp/domain_contacts_v1.rb
@@ -23,6 +23,13 @@ module Repp
                    :bad_request)
           end
 
+          if new_contact.invalid?
+            error!({ error: { type: 'invalid_request_error',
+                              param: 'new_contact_id',
+                              message: 'New contact must be valid' } },
+                   :bad_request)
+          end
+
           if current_contact == new_contact
             error!({ error: { type: 'invalid_request_error',
                               message: 'New contact ID must be different from current' \
diff --git a/test/fixtures/contacts.yml b/test/fixtures/contacts.yml
index 50befdcf8..b64dce039 100644
--- a/test/fixtures/contacts.yml
+++ b/test/fixtures/contacts.yml
@@ -76,7 +76,7 @@ not_in_use:
 
 invalid:
   name: any
-  code: any
+  code: invalid
   email: invalid@invalid.test
   auth_info: any
   registrar: bestnames
diff --git a/test/integration/api/domain_contacts_test.rb b/test/integration/api/domain_contacts_test.rb
index 8d619f969..a6d6376f7 100644
--- a/test/integration/api/domain_contacts_test.rb
+++ b/test/integration/api/domain_contacts_test.rb
@@ -95,6 +95,17 @@ class APIDomainContactsTest < ActionDispatch::IntegrationTest
                  JSON.parse(response.body, symbolize_names: true)
   end
 
+  def test_disallow_invalid_new_contact
+    patch '/repp/v1/domains/contacts', { current_contact_id: 'william-001',
+                                         new_contact_id: 'invalid' },
+          { 'HTTP_AUTHORIZATION' => http_auth_key }
+    assert_response :bad_request
+    assert_equal ({ error: { type: 'invalid_request_error',
+                             param: 'new_contact_id',
+                             message: 'New contact must be valid' } }),
+                 JSON.parse(response.body, symbolize_names: true)
+  end
+
   def test_disallow_self_replacement
     patch '/repp/v1/domains/contacts', { current_contact_id: 'william-001',
                                          new_contact_id: 'william-001' },