diff --git a/matrix_appservice_kakaotalk/kt/types/client/client_session.py b/matrix_appservice_kakaotalk/kt/types/client/client_session.py
index b2d08b5..a68e877 100644
--- a/matrix_appservice_kakaotalk/kt/types/client/client_session.py
+++ b/matrix_appservice_kakaotalk/kt/types/client/client_session.py
@@ -13,7 +13,7 @@
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
-from typing import NewType, Union
+from typing import NewType, Optional, Union
 
 from attr import dataclass
 
@@ -43,13 +43,13 @@ class LoginResult(SerializableAttrs):
     """Return value of TalkClient.login"""
     channelList: list[LoginDataItem]
     userId: Long
-    lastChannelId: Long
     lastTokenId: Long
     mcmRevision: int
     removedChannelIdList: list[Long]
     revision: int
     revisionInfo: str
     minLogId: Long
+    lastChannelId: Optional[Long] = None # NEW Made optional
     # TODO Consider catching SerializerError for channelList entries