diff --git a/lib/error.ts b/lib/error.ts
new file mode 100644
index 0000000..fc65893
--- /dev/null
+++ b/lib/error.ts
@@ -0,0 +1,6 @@
+export class NotFoundError extends Error {
+	constructor(url: URL) {
+		super(`Not found: ${url}`);
+		this.name = "NotFoundError";
+	}
+}
diff --git a/lib/feed-handler.ts b/lib/feed-handler.ts
index c635fde..e67c40b 100644
--- a/lib/feed-handler.ts
+++ b/lib/feed-handler.ts
@@ -1,5 +1,6 @@
 import { createResponse } from "itty-router";
-import { NotFoundError, convertFeed } from "./feed.js";
+import { NotFoundError } from "./error.js";
+import { convertFeed } from "./feed.js";
 import { Logger } from "./logger.js";
 
 type Config = {
diff --git a/lib/feed.test.ts b/lib/feed.test.ts
index b8282d1..ed57203 100644
--- a/lib/feed.test.ts
+++ b/lib/feed.test.ts
@@ -1,13 +1,13 @@
 import { strict as assert } from "node:assert";
 import test from "node:test";
 import { error, json } from "itty-router";
+import { NotFoundError } from "./error.js";
 import {
 	Convertor,
 	ConvertorConf,
 	FeedConf,
 	FeedFetcher,
 	FetcherConf,
-	NotFoundError,
 	convertFeed,
 } from "./feed.js";
 import { Fetcher as MediaFetcher } from "./media.js";
diff --git a/lib/feed.ts b/lib/feed.ts
index f5d9809..5f4c175 100644
--- a/lib/feed.ts
+++ b/lib/feed.ts
@@ -1,6 +1,7 @@
 import { PromisePool } from "@supercharge/promise-pool";
 import { z } from "zod";
 import { Podcast } from "../build/podcast/index.js";
+import { NotFoundError } from "./error.js";
 import { Fetcher as MediaFetcher } from "./media.js";
 
 const cardSchema = z.object({
@@ -77,13 +78,6 @@ export class FeedFetcher {
 	}
 }
 
-export class NotFoundError extends Error {
-	constructor(url: URL) {
-		super(`Not found: ${url}`);
-		this.name = "NotFoundError";
-	}
-}
-
 export type ConvertorConf = {
 	raiBaseUrl: URL;
 	poolSize: number;