diff --git a/src/utilities/RegistryFilter.ts b/src/utilities/RegistryFilter.ts
index e4472ec..e95e01a 100644
--- a/src/utilities/RegistryFilter.ts
+++ b/src/utilities/RegistryFilter.ts
@@ -70,25 +70,36 @@ class RegistryFilter<T extends RegistryEntry, K extends keyof T = keyof T> {
    * Filters entries **strictly** by their `area_id`.
    *
    * - Entries with a matching `area_id` are kept.
+   * - If `expandToDevice` is `true`, the device's `area_id` is evaluated if the entry's area_id doesn't match.
    * - If `areaId` is `undefined` (or omitted), entries without an `area_id` property are kept.
-   * - If `expandToDevice` is `true` and the entry's `area_id` is `undisclosed`, the device's `area_id` is used.
    *
    * @param {string | undefined} areaId - The area id to match.
-   * @param {boolean} [expandToDevice=true] - Whether to use the device's `area_id` if the entry has none.
+   * @param {boolean} [expandToDevice=true] - Whether to use the device's `area_id` if the entry's doesn't match.
+   *
+   * @remarks
+   * For area id `undisclosed`, the `area_id` of the entry's device may be `undisclosed` or `undefined`.
    */
   whereAreaId(areaId?: string, expandToDevice: boolean = true): this {
     const predicate = (entry: T) => {
       let deviceAreaId: string | null | undefined = undefined;
       const entryObject = entry as EntityRegistryEntry;
 
+      // Retrieve the device area ID only if expandToDevice is true
       if (expandToDevice && entryObject.device_id) {
         deviceAreaId = Registry.devices.find((device) => device.id === entryObject.device_id)?.area_id;
       }
 
-      if (areaId === 'undisclosed' || areaId === undefined) {
-        return entry.area_id === areaId && (!expandToDevice || deviceAreaId === areaId);
+      // Logic for 'undisclosed' areaId
+      if (areaId === 'undisclosed') {
+        return entry.area_id === areaId && (deviceAreaId === areaId || deviceAreaId === undefined);
       }
 
+      // Logic for undefined areaId
+      if (areaId === undefined) {
+        return entry.area_id === undefined && (!expandToDevice || deviceAreaId === undefined);
+      }
+
+      // Logic for any other areaId
       return entry.area_id === areaId || (expandToDevice && deviceAreaId === areaId);
     };