diff --git a/packages/foundkey-js/src/api.ts b/packages/foundkey-js/src/api.ts
index 923fbd304..8a9ff1fce 100644
--- a/packages/foundkey-js/src/api.ts
+++ b/packages/foundkey-js/src/api.ts
@@ -42,13 +42,15 @@ export class APIClient {
 	constructor(opts: {
 		origin: APIClient['origin'];
 		credential?: APIClient['credential'];
-		fetch?: APIClient['fetch'] | null | undefined;
+		fetch?: FetchLike;
 	}) {
 		this.origin = opts.origin;
 		this.credential = opts.credential;
-		// ネイティブ関数をそのまま変数に代入して使おうとするとChromiumではIllegal invocationエラーが発生するため、
-		// 環境で実装されているfetchを使う場合は無名関数でラップして使用する
-		this.fetch = opts.fetch || ((...args) => fetch(...args));
+		// Wrap a native function with an anonymous function when using
+		// environment-implemented fetch, because Chromium generates an
+		// Illegal invocation error if you try to use a native function by
+		// assigning it to a variable as it is.
+		this.fetch = opts.fetch || (((...args) => fetch(...args)) as FetchLike);
 	}
 
 	public request<E extends keyof Endpoints, P extends Endpoints[E]['req']>(
@@ -79,7 +81,7 @@ export class APIClient {
 				cache: 'no-cache',
 			}).then(async (res) => {
 				const body = res.status === 204 ? null : await res.json();
-	
+
 				if (res.status === 200) {
 					resolve(body);
 				} else if (res.status === 204) {
diff --git a/packages/foundkey-js/src/entities.ts b/packages/foundkey-js/src/entities.ts
index d2cbe8289..5cec05c99 100644
--- a/packages/foundkey-js/src/entities.ts
+++ b/packages/foundkey-js/src/entities.ts
@@ -135,9 +135,9 @@ export type Note = {
 	user: User;
 	userId: User['id'];
 	reply?: Note;
-	replyId: Note['id'];
+	replyId: Note['id'] | null;
 	renote?: Note;
-	renoteId: Note['id'];
+	renoteId: Note['id'] | null;
 	files: DriveFile[];
 	fileIds: DriveFile['id'][];
 	visibility: NoteVisibility;
@@ -475,9 +475,6 @@ export function isPureRenote(note: Note): boolean {
 	return note.renoteId != null
 		&& note.text == null
 		&& note.cw == null
-		&& (
-			note.fileIds == null
-			|| note.fileIds.length === 0
-		)
+		&& note.fileIds.length === 0
 		&& note.poll == null;
 }
diff --git a/packages/foundkey-js/src/streaming.ts b/packages/foundkey-js/src/streaming.ts
index 0892db9d9..8f397f720 100644
--- a/packages/foundkey-js/src/streaming.ts
+++ b/packages/foundkey-js/src/streaming.ts
@@ -34,14 +34,13 @@ export default class Stream extends EventEmitter<StreamEvents> {
 
 	constructor(origin: string, user: { token: string; } | null, options?: {
 		WebSocket?: any;
-	}) {
+	} = {}) {
 		super();
-		options = options || { };
 
 		const query = urlQuery({
 			i: user?.token,
-			
-			// To prevent cache of an HTML such as error screen
+
+			// cache busting parameter
 			_t: Date.now(),
 		});