diff --git a/packages/client/src/components/MkNotifications.vue b/packages/client/src/components/MkNotifications.vue
index c8b54f4074..7b63b34197 100644
--- a/packages/client/src/components/MkNotifications.vue
+++ b/packages/client/src/components/MkNotifications.vue
@@ -43,7 +43,7 @@
 
 <script lang="ts" setup>
 import { computed, onMounted, onUnmounted, ref } from "vue";
-import type { entities, notificationTypes } from "firefish-js";
+import type { StreamTypes, entities, notificationTypes } from "firefish-js";
 import MkPagination from "@/components/MkPagination.vue";
 import XNotification from "@/components/MkNotification.vue";
 import XList from "@/components/MkDateSeparatedList.vue";
@@ -98,7 +98,7 @@ const onNotification = (notification: entities.Notification) => {
 	}
 };
 
-let connection;
+let connection: StreamTypes.ChannelOf<"main"> | undefined;
 
 onMounted(() => {
 	connection = stream.useChannel("main");
diff --git a/packages/client/src/components/MkTimeline.vue b/packages/client/src/components/MkTimeline.vue
index 456a481fa2..10f90c1dd1 100644
--- a/packages/client/src/components/MkTimeline.vue
+++ b/packages/client/src/components/MkTimeline.vue
@@ -44,7 +44,7 @@
 
 <script lang="ts" setup>
 import { computed, onUnmounted, provide, ref } from "vue";
-import type { entities } from "firefish-js";
+import type { entities, StreamTypes } from "firefish-js";
 import MkPullToRefresh from "@/components/MkPullToRefresh.vue";
 import XNotes from "@/components/MkNotes.vue";
 import MkInfo from "@/components/MkInfo.vue";
@@ -97,13 +97,16 @@ let query: {
 } = {};
 
 // FIXME: The type defination is wrong here, need fix
-let connection: {
-	on: (
-		arg0: string,
-		arg1: { (note: any): void; (note: any): void; (note: any): void },
-	) => void;
-	dispose: () => void;
-};
+let connection: 
+	| StreamTypes.ChannelOf<"antenna">
+	| StreamTypes.ChannelOf<"homeTimeline">
+	| StreamTypes.ChannelOf<"recommendedTimeline">
+	| StreamTypes.ChannelOf<"hybridTimeline">
+	| StreamTypes.ChannelOf<"globalTimeline">
+	| StreamTypes.ChannelOf<"main">
+	| StreamTypes.ChannelOf<"userList">
+	| StreamTypes.ChannelOf<"channel">
+
 let connection2: { dispose: () => void } | null;
 
 let tlHint: string;
diff --git a/packages/firefish-js/src/streaming.ts b/packages/firefish-js/src/streaming.ts
index 42fea4fca6..407984205b 100644
--- a/packages/firefish-js/src/streaming.ts
+++ b/packages/firefish-js/src/streaming.ts
@@ -236,14 +236,14 @@ export default class Stream extends EventEmitter<StreamEvents> {
 // TODO: これらのクラスを Stream クラスの内部クラスにすれば余計なメンバをpublicにしないで済むかも？
 // もしくは @internal を使う？ https://www.typescriptlang.org/tsconfig#stripInternal
 class Pool {
-	public channel: string;
+	public channel: keyof Channels;
 	public id: string;
 	protected stream: Stream;
 	public users = 0;
 	private disposeTimerId: any;
 	private isConnected = false;
 
-	constructor(stream: Stream, channel: string, id: string) {
+	constructor(stream: Stream, channel: keyof Channels, id: string) {
 		this.channel = channel;
 		this.stream = stream;
 		this.id = id;
@@ -301,7 +301,7 @@ class Pool {
 export abstract class Connection<
 	Channel extends AnyOf<Channels> = any,
 > extends EventEmitter<Channel["events"]> {
-	public channel: string;
+	public channel: keyof Channels;
 	protected stream: Stream;
 	public abstract id: string;
 
@@ -309,7 +309,7 @@ export abstract class Connection<
 	public inCount = 0; // for debug
 	public outCount = 0; // for debug
 
-	constructor(stream: Stream, channel: string, name?: string) {
+	constructor(stream: Stream, channel: keyof Channels, name?: string) {
 		super();
 
 		this.stream = stream;
@@ -342,7 +342,7 @@ class SharedConnection<
 		return this.pool.id;
 	}
 
-	constructor(stream: Stream, channel: string, pool: Pool, name?: string) {
+	constructor(stream: Stream, channel: keyof Channels, pool: Pool, name?: string) {
 		super(stream, channel, name);
 
 		this.pool = pool;
@@ -364,7 +364,7 @@ class NonSharedConnection<
 
 	constructor(
 		stream: Stream,
-		channel: string,
+		channel: keyof Channels,
 		id: string,
 		params: Channel["params"],
 	) {
diff --git a/packages/firefish-js/src/streaming.types.ts b/packages/firefish-js/src/streaming.types.ts
index e9be8622af..18c7682608 100644
--- a/packages/firefish-js/src/streaming.types.ts
+++ b/packages/firefish-js/src/streaming.types.ts
@@ -10,6 +10,7 @@ import type {
 	User,
 	UserGroup,
 } from "./entities";
+import type { Connection } from "./streaming";
 
 type FIXME = any;
 
@@ -199,3 +200,5 @@ export type BroadcastEvents = {
 		emoji: CustomEmoji;
 	}) => void;
 };
+
+export type ChannelOf<C extends keyof Channels> = Connection<Channels[C]>;