diff --git a/src/middlewared/middlewared/plugins/smb_/groupmap.py b/src/middlewared/middlewared/plugins/smb_/groupmap.py
index 175325f487b09..892bf5328037c 100644
--- a/src/middlewared/middlewared/plugins/smb_/groupmap.py
+++ b/src/middlewared/middlewared/plugins/smb_/groupmap.py
@@ -5,10 +5,11 @@
 from middlewared.service import Service, job, private
 from middlewared.service_exception import CallError
 from middlewared.utils.sid import (
-    BASE_RID_USER,
     db_id_to_rid,
     get_domain_rid,
     lsa_sidtype,
+    sid_is_valid,
+    BASE_RID_USER,
     DomainRid
 )
 from middlewared.utils.tdb import (
@@ -288,6 +289,16 @@ def groupmap_list(self):
 
         return rv
 
+    @private
+    def groupmap_listmem(self, sid):
+        if not sid_is_valid(sid):
+            raise ValueError(f'{sid}: not a valid SID')
+
+        data = list_foreign_group_memberships(GroupmapFile.DEFAULT, sid)
+        assert data.sid == sid
+
+        return data.members
+
     @private
     def sync_builtins(self, to_add):
         idmap_backend = self.middleware.call_sync("smb.getparm", "idmap config * : backend", "GLOBAL")
@@ -334,9 +345,7 @@ def synchronize_group_mappings(self, job, bypass_sentinel_check=False):
 
         groupmap = self.groupmap_list()
 
-        groups = self.middleware.call_sync('group.query', [
-            ('builtin', '=', False), ('local', '=', True), ('smb', '=', True)
-        ])
+        groups = self.middleware.call_sync('group.query', [('local', '=', True), ('smb', '=', True)])
         groups.append(self.middleware.call_sync('group.query', [('gid', '=', 545), ('local', '=', True)], {'get': True}))
         gid_set = {x["gid"] for x in groups}
 
diff --git a/tests/api2/test_smb_groupmap.py b/tests/api2/test_smb_groupmap.py
index bb04f799697e5..622c86fe0b37f 100644
--- a/tests/api2/test_smb_groupmap.py
+++ b/tests/api2/test_smb_groupmap.py
@@ -16,6 +16,11 @@
     assert rid == expected_rid
 
     groupmap = call('smb.groupmap_list')
+    assert str(entry['gid']) in groupmap['local_builtins']
+    assert groupmap['local_builtins'][str(entry['gid'])]['sid'] == entry['sid']
+
+    members = call('smb.groupmap_listmem', expected_memberof)
+    assert entry['sid'] in members
 
 
 test__builtin_users_account():
@@ -24,6 +29,9 @@
     rid = int(entry['sid'].split('-')[-1])
     assert rid == entry['id'] + BASE_RID_GROUP 
 
+    members_dom_users = call('smb.groupmap_listmem', 'S-1-5-32-545')
+    assert entry['sid'] in members_dom_users
+
 
 test__new_group():
     with group({"name": "group1"}) as g:
@@ -51,6 +59,5 @@
         new = call('group.get_instance', g['id'])
         assert new['sid'] == g['sid'] 
 
-        # 
         groupmap = call('smb.groupmap_list')
-        assert new['gid'] in groupmap['local']
+        assert str(new['gid']) in groupmap['local']