diff --git a/app/main/views/invites.py b/app/main/views/invites.py
index 8c3eb427e..f6a070ea0 100644
--- a/app/main/views/invites.py
+++ b/app/main/views/invites.py
@@ -105,7 +105,7 @@ def accept_org_invite(token):
     if existing_user:
         invited_org_user.accept_invite()
         if existing_user not in organisation_users:
-            invited_org_user.add_to_organisation()
+            invited_org_user.add_to_organisation(existing_user.id)
         return redirect(url_for('main.organisation_dashboard', org_id=invited_org_user.organisation))
     else:
         return redirect(url_for('main.register_from_org_invite'))
diff --git a/app/models/user.py b/app/models/user.py
index e0e46e620..062d4e983 100644
--- a/app/models/user.py
+++ b/app/models/user.py
@@ -584,8 +584,8 @@ class InvitedOrgUser(JSONModel):
     def accept_invite(self):
         org_invite_api_client.accept_invite(self.organisation, self.id)
 
-    def add_to_organisation(self):
-        user_api_client.add_user_to_organisation(self.organisation, self.id)
+    def add_to_organisation(self, user_id):
+        user_api_client.add_user_to_organisation(self.organisation, user_id)
 
 
 class AnonymousUser(AnonymousUserMixin):
diff --git a/tests/app/main/views/organisations/test_organisation_invites.py b/tests/app/main/views/organisations/test_organisation_invites.py
index 7d623dbfa..dd88e1aea 100644
--- a/tests/app/main/views/organisations/test_organisation_invites.py
+++ b/tests/app/main/views/organisations/test_organisation_invites.py
@@ -1,6 +1,5 @@
 from datetime import datetime, timedelta
 from unittest.mock import ANY
-from uuid import UUID
 
 import pytest
 from bs4 import BeautifulSoup
@@ -84,7 +83,7 @@ def test_invite_org_user_errors_when_same_email_as_inviter(
     assert normalize_spaces(page.select_one('.error-message').text) == 'You can’t send an invitation to yourself'
 
 
-def test_accepted_invite_when_user_already_logged_in(
+def test_accepted_invite_when_other_user_already_logged_in(
     client_request,
     mock_check_org_invite_token
 ):
@@ -165,6 +164,7 @@ def test_existing_user_invite_already_is_member_of_organisation(
 
 def test_existing_user_invite_not_a_member_of_organisation(
     client,
+    api_user_active,
     mock_check_org_invite_token,
     mock_get_user_by_email,
     mock_get_users_for_organisation,
@@ -186,7 +186,7 @@ def test_existing_user_invite_not_a_member_of_organisation(
     mock_get_users_for_organisation.assert_called_once_with(ORGANISATION_ID)
     mock_add_user_to_organisation.assert_called_once_with(
         ORGANISATION_ID,
-        str(UUID(bytes=b'sample_org_invit', version=4))
+        api_user_active['id'],
     )