diff --git a/matrix_appservice_kakaotalk/portal.py b/matrix_appservice_kakaotalk/portal.py
index 0d74e0a..5364535 100644
--- a/matrix_appservice_kakaotalk/portal.py
+++ b/matrix_appservice_kakaotalk/portal.py
@@ -33,7 +33,7 @@ import asyncio
 import re
 import time
 
-from attr import dataclass
+from attr import dataclass, evolve
 
 from mautrix.appservice import IntentAPI
 from mautrix.bridge import BasePortal, NotificationDisabler, async_getter_lock
@@ -420,7 +420,7 @@ class Portal(DBPortal, BasePortal):
         sender_intent = sender.intent_for(self) if sender else self.main_intent
         admin_level = orig_power_levels.get_user_level(sender_intent.mxid)
         demoter_ids: list[UserID] = []
-        power_levels = PowerLevelStateEventContent(**orig_power_levels.serialize())
+        power_levels = evolve(orig_power_levels)
         for user_id, new_level in user_power_levels.items():
             curr_level = orig_power_levels.get_user_level(user_id)
             if curr_level < admin_level or user_id == sender_intent.mxid:
@@ -436,7 +436,7 @@ class Portal(DBPortal, BasePortal):
         except:
             self.log.exception("Failed to set power level")
             if demoter_ids:
-                power_levels = PowerLevelStateEventContent(**orig_power_levels.serialize())
+                power_levels = evolve(orig_power_levels)
         for demoter_id in demoter_ids:
             power_levels.set_user_level(demoter_id, user_power_levels[demoter_id])
             try: