diff --git a/incognia/api.py b/incognia/api.py
index e926cc1..994d360 100644
--- a/incognia/api.py
+++ b/incognia/api.py
@@ -207,7 +207,9 @@ def register_login(self,
                        policy_id: Optional[str] = None,
                        device_os: Optional[str] = None,
                        app_version: Optional[str] = None,
+                       custom_properties: Optional[dict] = None,
                        person_id: Optional[PersonID] = None) -> dict:
+
         if not request_token:
             raise IncogniaError('request_token is required.')
         if not account_id:
@@ -236,6 +238,7 @@ def register_login(self,
                 'policy_id': policy_id,
                 'device_os': device_os.lower() if device_os is not None else None,
                 'app_version': app_version,
+                'custom_properties': custom_properties,
                 'person_id': person_id,
             }
             data = encode(body)
diff --git a/tests/test_api.py b/tests/test_api.py
index dab3398..3b41c2a 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -243,7 +243,8 @@ class TestIncogniaAPI(TestCase):
         'policy_id': f'{POLICY_ID}',
         'device_os': f'{DEVICE_OS.lower()}',
         'app_version': f'{APP_VERSION}',
-        'person_id': PERSON_ID
+        'custom_properties': CUSTOM_PROPERTIES,
+        'person_id': PERSON_ID,
     })
     REGISTER_VALID_WEB_LOGIN_DATA: Final[bytes] = encode({
         'type': 'login',
@@ -771,6 +772,7 @@ def test_register_login_with_all_fields_should_work(
                                               policy_id=self.POLICY_ID,
                                               device_os=self.DEVICE_OS,
                                               app_version=self.APP_VERSION,
+                                              custom_properties=self.CUSTOM_PROPERTIES,
                                               person_id=self.PERSON_ID)
 
         mock_token_manager_get.assert_called()