diff --git a/ceo_common/interfaces/ILDAPService.py b/ceo_common/interfaces/ILDAPService.py
index 09738fb..84ee9ad 100644
--- a/ceo_common/interfaces/ILDAPService.py
+++ b/ceo_common/interfaces/ILDAPService.py
@@ -33,6 +33,11 @@ class ILDAPService(Interface):
         A new UID and GID will be generated and returned in the new user.
         """
 
+    def get_groups_for_user(username: str) -> List[str]:
+        """
+        Get a list of the groups to which the user belongs.
+        """
+
     def remove_user(user: IUser):
         """Remove this user from the database."""
 
diff --git a/ceod/api/members.py b/ceod/api/members.py
index 167434f..8394ee7 100644
--- a/ceod/api/members.py
+++ b/ceod/api/members.py
@@ -1,9 +1,9 @@
-from flask import Blueprint, g, request
+from flask import Blueprint, request
 from flask.json import jsonify
 from zope import component
 
 from .utils import authz_restrict_to_staff, authz_restrict_to_syscom, \
-    user_is_in_group, requires_authentication_no_realm, \
+    user_is_in_group, requires_authentication_no_realm, requires_admin_creds, \
     create_streaming_response, development_only, is_truthy
 from ceo_common.errors import BadRequest, UserAlreadySubscribedError, UserNotSubscribedError
 from ceo_common.interfaces import ILDAPService, IConfig, IMailService
@@ -20,8 +20,12 @@ logger = logger_factory(__name__)
 
 
 @bp.route('/', methods=['POST'], strict_slashes=False)
+@requires_admin_creds
 @authz_restrict_to_staff
 def create_user():
+    # We need to use the admin creds here because office members may not
+    # directly create new LDAP records.
+
     body = request.get_json(force=True)
     terms = body.get('terms')
     non_member_terms = body.get('non_member_terms')
@@ -31,10 +35,6 @@ def create_user():
         if not body.get(attr):
             raise BadRequest(f"Attribute '{attr}' is missing or empty")
 
-    # We need to use the admin creds here because office members may not
-    # directly create new LDAP records.
-    g.need_admin_creds = True
-
     if terms:
         logger.info(f"Creating member {body['uid']} for terms {terms}")
     else:
@@ -86,19 +86,19 @@ def patch_user(auth_user: str, username: str):
 
 
 @bp.route('/<username>/renew', methods=['POST'])
+@requires_admin_creds
 @authz_restrict_to_staff
 def renew_user(username: str):
+    # We need to use the admin creds here because office members should
+    # not be able to directly modify the shadowExpire field; this could
+    # prevent syscom members from logging into the machines.
+
     body = request.get_json(force=True)
     terms = body.get('terms')
     non_member_terms = body.get('non_member_terms')
     if (terms and non_member_terms) or not (terms or non_member_terms):
         raise BadRequest('Must specify either terms or non-member terms')
 
-    # We need to use the admin creds here because office members should
-    # not be able to directly modify the shadowExpire field; this could
-    # prevent syscom members from logging into the machines.
-    g.need_admin_creds = True
-
     ldap_srv = component.getUtility(ILDAPService)
     cfg = component.getUtility(IConfig)
     user = ldap_srv.get_user(username)
diff --git a/ceod/api/utils.py b/ceod/api/utils.py
index 01ba4fa..394cacf 100644
--- a/ceod/api/utils.py
+++ b/ceod/api/utils.py
@@ -1,12 +1,9 @@
 import functools
-import grp
 import json
-import os
-import pwd
 import traceback
 from typing import Callable, List
 
-from flask import current_app, stream_with_context
+from flask import current_app, g, stream_with_context
 from zope import component
 
 from .spnego import requires_authentication
@@ -40,9 +37,24 @@ def requires_authentication_no_realm(f: Callable) -> Callable:
     return wrapper
 
 
-def user_is_in_group(user: str, group: str) -> bool:
-    """Returns True if `user` is in `group`, False otherwise."""
-    return user in grp.getgrnam(group).gr_mem
+def requires_admin_creds(f: Callable) -> Callable:
+    """
+    Forces the next LDAP connection to use the admin Kerberos credentials.
+    This must be used BEFORE any of the authz decorators, since those
+    may require an LDAP connection, which will get cached for later use.
+    """
+    @functools.wraps(f)
+    def wrapper(*args, **kwargs):
+        g.need_admin_creds = True
+        return f(*args, **kwargs)
+    return wrapper
+
+
+def user_is_in_group(username: str, group_name: str) -> bool:
+    """Returns True if `username` is in `group_name`, False otherwise."""
+    ldap_srv = component.getUtility(ILDAPService)
+    group = ldap_srv.get_group(group_name)
+    return username in group.members
 
 
 def authz_restrict_to_groups(f: Callable, allowed_groups: List[str]) -> Callable:
@@ -51,8 +63,6 @@ def authz_restrict_to_groups(f: Callable, allowed_groups: List[str]) -> Callable
     specified groups.
     """
 
-    allowed_group_ids = [grp.getgrnam(g).gr_gid for g in allowed_groups]
-
     @requires_authentication_no_realm
     @functools.wraps(f)
     def wrapper(_username: str, *args, **kwargs):
@@ -62,15 +72,14 @@ def authz_restrict_to_groups(f: Callable, allowed_groups: List[str]) -> Callable
         if username.startswith('ceod/'):
             # ceod services are always allowed to make internal calls
             return f(*args, **kwargs)
-        for gid in os.getgrouplist(username, pwd.getpwnam(username).pw_gid):
-            if gid in allowed_group_ids:
+        ldap_srv = component.getUtility(ILDAPService)
+        for group_name in ldap_srv.get_groups_for_user(username):
+            if group_name in allowed_groups:
                 return f(*args, **kwargs)
         logger.debug(
             f"User '{username}' denied since they are not in one of {allowed_groups}"
         )
-        return {
-            'error': f'You must be in one of {allowed_groups}'
-        }, 403
+        return {'error': f'You must be in one of {allowed_groups}'}, 403
 
     return wrapper
 
diff --git a/ceod/model/LDAPService.py b/ceod/model/LDAPService.py
index 74c79f3..a569991 100644
--- a/ceod/model/LDAPService.py
+++ b/ceod/model/LDAPService.py
@@ -98,6 +98,13 @@ class LDAPService:
         entry = self._get_readable_entry_for_group(conn, cn)
         return Group.deserialize_from_ldap(entry)
 
+    def get_groups_for_user(self, username: str) -> List[str]:
+        conn = self._get_ldap_conn()
+        conn.search(self.ldap_groups_base,
+                    f'(uniqueMember={self.uid_to_dn(username)})',
+                    attributes=['cn'])
+        return [entry.cn.value for entry in conn.entries]
+
     def get_display_info_for_users(self, usernames: List[str]) -> List[Dict[str, str]]:
         if not usernames:
             return []
diff --git a/tests/ceo/cli/test_groups.py b/tests/ceo/cli/test_groups.py
index 462fc99..50c4931 100644
--- a/tests/ceo/cli/test_groups.py
+++ b/tests/ceo/cli/test_groups.py
@@ -117,8 +117,7 @@ def test_groups_multiple_members(cli_setup, new_user_gen):
 def test_groups_with_auxiliary_groups_and_mailing_lists(cli_setup, ldap_user):
     runner = CliRunner()
     # make sure auxiliary groups + mailing lists exist in ceod_test_local.ini
-    create_group('syscom', 'Systems Committee')
-    create_group('office', 'Office')
+    create_group('adm', 'Administrators')
     create_group('staff', 'Staff')
 
     runner = CliRunner()
@@ -131,7 +130,7 @@ def test_groups_with_auxiliary_groups_and_mailing_lists(cli_setup, ldap_user):
         "Add user to auxiliary groups... Done\n"
         "Subscribe user to auxiliary mailing lists... Done\n"
         "Transaction successfully completed.\n"
-        f"Added {ldap_user.uid} to syscom, office, staff\n"
+        f"Added {ldap_user.uid} to syscom, adm, staff\n"
         f"Subscribed {ldap_user.uid} to syscom@csclub.internal, syscom-alerts@csclub.internal\n"
     )
     assert result.exit_code == 0
@@ -147,7 +146,7 @@ def test_groups_with_auxiliary_groups_and_mailing_lists(cli_setup, ldap_user):
         "Remove user from auxiliary groups... Done\n"
         "Unsubscribe user from auxiliary mailing lists... Done\n"
         "Transaction successfully completed.\n"
-        f"Removed {ldap_user.uid} from syscom, office, staff\n"
+        f"Removed {ldap_user.uid} from syscom, adm, staff\n"
         f"Unsubscribed {ldap_user.uid} from syscom@csclub.internal, syscom-alerts@csclub.internal\n"
     )
     assert result.exit_code == 0
@@ -167,6 +166,5 @@ def test_groups_with_auxiliary_groups_and_mailing_lists(cli_setup, ldap_user):
     assert result.exit_code == 0
     assert 'Unsubscribed' not in result.output
 
-    delete_group('syscom')
-    delete_group('office')
+    delete_group('adm')
     delete_group('staff')
diff --git a/tests/ceo/cli/test_members.py b/tests/ceo/cli/test_members.py
index 09b5acb..cf13a38 100644
--- a/tests/ceo/cli/test_members.py
+++ b/tests/ceo/cli/test_members.py
@@ -4,6 +4,7 @@ import shutil
 from datetime import datetime, timedelta
 
 from click.testing import CliRunner
+import ldap3
 
 from ceo.cli import cli
 from ceo_common.model import Term
@@ -146,7 +147,7 @@ def test_members_pwreset(cli_setup, ldap_user, krb_user):
     assert expected_pat.match(result.output) is not None
 
 
-def test_members_expire(cli_setup, app_process, ldap_user, syscom_group):
+def test_members_expire(cli_setup, app_process, ldap_user):
     runner = CliRunner()
 
     try:
@@ -172,12 +173,17 @@ def test_members_expire(cli_setup, app_process, ldap_user, syscom_group):
         restore_datetime_in_app_process(app_process)
 
 
-def test_members_remindexpire(cli_setup, app_process, ldap_user):
+def test_members_remindexpire(cfg, cli_setup, app_process, ldap_conn, ldap_user):
     runner = CliRunner()
     term = Term(ldap_user.terms[0])
+    test_date = (term + 1).to_datetime()
+    # Add a term to ctdalek so that he doesn't show up in the results
+    base_dn = cfg.get('ldap_users_base')
+    ldap_conn.modify(
+        f'uid=ctdalek,{base_dn}',
+        {'term': [(ldap3.MODIFY_ADD, [str(term + 1)])]})
 
     try:
-        test_date = (term + 1).to_datetime()
         set_datetime_in_app_process(app_process, test_date)
         result = runner.invoke(cli, ['members', 'remindexpire', '--dry-run'])
         assert result.exit_code == 0
@@ -200,3 +206,7 @@ def test_members_remindexpire(cli_setup, app_process, ldap_user):
         assert result.output == "No members are pending expiration.\n"
     finally:
         restore_datetime_in_app_process(app_process)
+
+    ldap_conn.modify(
+        f'uid=ctdalek,{base_dn}',
+        {'term': [(ldap3.MODIFY_DELETE, [str(term + 1)])]})
diff --git a/tests/ceod/api/test_groups.py b/tests/ceod/api/test_groups.py
index e13b172..67388ea 100644
--- a/tests/ceod/api/test_groups.py
+++ b/tests/ceod/api/test_groups.py
@@ -125,7 +125,8 @@ def test_api_group_auxiliary(cfg, client, ldap_user, g_admin_ctx):
     group_names = ['syscom'] + aux_groups
     groups = []
     with g_admin_ctx():
-        for group_name in group_names:
+        # the syscom group should already exist, since we need it for auth
+        for group_name in aux_groups:
             group = Group(
                 cn=group_name,
                 gid_number=min_uid,
@@ -161,4 +162,5 @@ def test_api_group_auxiliary(cfg, client, ldap_user, g_admin_ctx):
 
     with g_admin_ctx():
         for group in groups:
-            group.remove_from_ldap()
+            if group.cn != 'syscom':
+                group.remove_from_ldap()
diff --git a/tests/ceod/api/test_members.py b/tests/ceod/api/test_members.py
index 7818353..8417cc6 100644
--- a/tests/ceod/api/test_members.py
+++ b/tests/ceod/api/test_members.py
@@ -241,7 +241,7 @@ def test_authz_check(client, create_user_result):
 
 
 @pytest.mark.parametrize('term_attr', ['terms', 'non_member_terms'])
-def test_expire(client, new_user, term_attr, syscom_group, ldap_conn):
+def test_expire(client, new_user, term_attr, ldap_conn):
     assert new_user.shadowExpire is None
     current_term = Term.current()
     start_of_current_term = current_term.to_datetime()
@@ -281,6 +281,7 @@ def test_expire(client, new_user, term_attr, syscom_group, ldap_conn):
 
             status, data = client.post('/api/members/expire?dry_run=yes')
             assert status == 200
+            print(data)
             assert (data == [uid]) == should_expire
 
             _, user = client.get(f'/api/members/{uid}')
@@ -306,15 +307,13 @@ def test_expire(client, new_user, term_attr, syscom_group, ldap_conn):
 
 
 @pytest.mark.parametrize('in_syscom', [True, False])
-def test_expire_syscom_member(client, new_user, syscom_group, g_admin_ctx, ldap_conn, in_syscom):
+def test_expire_syscom_member(client, new_user, ldap_conn, in_syscom):
     uid = new_user.uid
     start_of_current_term = Term.current().to_datetime()
     if in_syscom:
         group_dn = new_user.ldap_srv.group_cn_to_dn('syscom')
         user_dn = new_user.ldap_srv.uid_to_dn(uid)
-        changes = {
-            'uniqueMember': [(ldap3.MODIFY_ADD, [user_dn])]
-        }
+        changes = {'uniqueMember': [(ldap3.MODIFY_ADD, [user_dn])]}
         ldap_conn.modify(group_dn, changes)
     with patch.object(ceo_common.utils, 'get_current_datetime') as datetime_mock:
         datetime_mock.return_value = start_of_current_term + datetime.timedelta(days=160)
@@ -324,9 +323,12 @@ def test_expire_syscom_member(client, new_user, syscom_group, g_admin_ctx, ldap_
             assert data == []
         else:
             assert data == [uid]
+    if in_syscom:
+        changes = {'uniqueMember': [(ldap3.MODIFY_DELETE, [user_dn])]}
+        ldap_conn.modify(group_dn, changes)
 
 
-def test_office_member(cfg, client):
+def test_office_member(cfg, client, office_user):
     admin_principal = cfg.get('ldap_admin_principal')
     ccache_file = cfg.get('ldap_admin_principal_ccache')
     if os.path.isfile(ccache_file):
@@ -367,11 +369,17 @@ def test_office_member(cfg, client):
     assert status == 200
 
 
-def test_membership_renewal_reminder(client, mock_mail_server):
+def test_membership_renewal_reminder(cfg, client, mock_mail_server, ldap_conn):
     uids = ['test3', 'test4']
     # fast-forward by one term so that we don't clash with the other users
     # created by other tests
     term = Term.current() + 1
+    # Add some terms to ctdalek so that he doesn't show up in the API calls below
+    base_dn = cfg.get('ldap_users_base')
+    ldap_conn.modify(
+        f'uid=ctdalek,{base_dn}',
+        {'term': [(ldap3.MODIFY_ADD, [str(term), str(term + 1), str(term + 2)])]})
+
     with patch.object(ceo_common.utils, 'get_current_datetime') as datetime_mock:
         datetime_mock.return_value = term.to_datetime()
         for uid in uids:
@@ -433,3 +441,7 @@ def test_membership_renewal_reminder(client, mock_mail_server):
         status, _ = client.delete(f'/api/members/{uid}')
         assert status == 200
     mock_mail_server.messages.clear()
+
+    ldap_conn.modify(
+        f'uid=ctdalek,{base_dn}',
+        {'term': [(ldap3.MODIFY_DELETE, [str(term), str(term + 1), str(term + 2)])]})
diff --git a/tests/ceod_test_local.ini b/tests/ceod_test_local.ini
index 8e78cef..8adc851 100644
--- a/tests/ceod_test_local.ini
+++ b/tests/ceod_test_local.ini
@@ -27,7 +27,8 @@ server_url = ldap://auth1.csclub.internal
 base = ou=TestUWLDAP,dc=csclub,dc=internal
 
 [members]
-min_id = 20001
+# 20000 is ctdalek, 20001 is office1
+min_id = 20002
 max_id = 29999
 home = /tmp/test_users
 skel = /users/skel
@@ -49,7 +50,7 @@ api_password = mailman3
 new_member_list = csc-general
 
 [auxiliary groups]
-syscom = office,staff
+syscom = adm,staff
 
 [auxiliary mailing lists]
 syscom = syscom,syscom-alerts
diff --git a/tests/conftest.py b/tests/conftest.py
index 224b742..e3c3c3a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -159,6 +159,70 @@ def ldap_conn(cfg) -> ldap3.Connection:
     return conn
 
 
+@pytest.fixture
+def office_user(cfg, ldap_conn):
+    users_base = cfg.get('ldap_users_base')
+    home_parent = cfg.get('members_home')
+    ldap_conn.add(
+        f'uid=office1,{users_base}',
+        ['top', 'account', 'posixAccount', 'shadowAccount', 'member'],
+        {
+            'uid': 'office1',
+            'uidNumber': '20001',
+            'gidNumber': '20001',
+            'homeDirectory': f'{home_parent}/office1',
+            'loginShell': '/bin/bash',
+            'cn': 'Office One',
+            'givenName': 'Office',
+            'sn': 'One',
+            'program': 'Math',
+            'term': [str(Term.current())],
+        }
+    )
+    yield
+    ldap_conn.delete(f'uid=office1,{users_base}')
+
+
+def add_stock_groups_and_users(cfg: IConfig, conn: ldap3.Connection):
+    users_base = cfg.get('ldap_users_base')
+    groups_base = cfg.get('ldap_groups_base')
+    home_parent = cfg.get('members_home')
+    conn.add(
+        f'cn=syscom,{groups_base}',
+        ['top', 'group', 'posixGroup'],
+        {
+            'cn': 'syscom',
+            'gidNumber': '10001',
+            'uniqueMember': [f'uid=ctdalek,{users_base}']
+        }
+    )
+    conn.add(
+        f'uid=ctdalek,{users_base}',
+        ['top', 'account', 'posixAccount', 'shadowAccount', 'member'],
+        {
+            'uid': 'ctdalek',
+            'uidNumber': '20000',
+            'gidNumber': '20000',
+            'homeDirectory': f'{home_parent}/ctdalek',
+            'loginShell': '/bin/bash',
+            'cn': 'Calum T. Dalek',
+            'givenName': 'Calum',
+            'sn': 'Dalek',
+            'program': 'Math',
+            'term': [str(Term.current())],
+        }
+    )
+    conn.add(
+        f'cn=office,{groups_base}',
+        ['top', 'group', 'posixGroup'],
+        {
+            'cn': 'office',
+            'gidNumber': '10003',
+            'uniqueMember': [f'uid=office1,{users_base}']
+        }
+    )
+
+
 @pytest.fixture(scope='session')
 def ldap_srv_session(cfg, krb_srv, ldap_conn):
     conn = ldap_conn
@@ -169,6 +233,8 @@ def ldap_srv_session(cfg, krb_srv, ldap_conn):
     for base_dn in [users_base, groups_base, sudo_base]:
         delete_subtree(conn, base_dn)
         conn.add(base_dn, 'organizationalUnit')
+    # Needed for API authentication
+    add_stock_groups_and_users(cfg, conn)
 
     _ldap_srv = LDAPService()
     component.getGlobalSiteManager().registerUtility(_ldap_srv, ILDAPService)
@@ -496,20 +562,6 @@ def ldap_group(simple_group, g_admin_ctx):
         simple_group.remove_from_ldap()
 
 
-@pytest.fixture
-def syscom_group(g_admin_ctx):
-    group = Group(
-        cn='syscom',
-        gid_number=10001,
-        user_cn='Systems Committee'
-    )
-    with g_admin_ctx():
-        group.add_to_ldap()
-    yield group
-    with g_admin_ctx():
-        group.remove_from_ldap()
-
-
 @pytest.fixture
 def uwldap_user(cfg, uwldap_srv, ldap_conn):
     conn = ldap_conn