diff --git a/api/src/dooris_api/app.py b/api/src/dooris_api/app.py
index 9be8164..f239fa5 100644
--- a/api/src/dooris_api/app.py
+++ b/api/src/dooris_api/app.py
@@ -233,11 +233,17 @@ async def list_locks(ccujack: deps.CCUJackClient) -> List[models.Lock]:
                     case "UNREACH":
                         status_data["is_unreachable"] = value.v
 
+        main_lock = app_config.get().main_lock or ""
+        is_main_lock = (
+            i_lock.identifier.lower() == main_lock.lower()
+            or i_lock.title.lower() == main_lock.lower()
+        )
         result.append(
             models.Lock(
                 id=i_lock.identifier,
                 name=i_lock.title,
                 status=models.LockStatus(**status_data),
+                is_main_lock=is_main_lock,
             )
         )
 
diff --git a/api/src/dooris_api/models.py b/api/src/dooris_api/models.py
index ee95233..ae603c4 100644
--- a/api/src/dooris_api/models.py
+++ b/api/src/dooris_api/models.py
@@ -54,7 +54,6 @@ class LockStatus(BaseModel):
     is_unreachable: bool
     is_low_battery: bool
     is_error_jammed: bool
-    is_main_lock: bool
     lock_target_level: Literal["locked", "unlocked", "open"]
     lock_state: Literal["unknown", "locked", "unlocked"]
     activity_state: Literal["unknown", "locking", "unlocking", "stable"]
@@ -63,6 +62,7 @@ class LockStatus(BaseModel):
 class Lock(BaseModel):
     name: str
     id: str
+    is_main_lock: bool
     status: LockStatus