diff --git a/src/github/utils/plugins.ts b/src/github/utils/plugins.ts
index 2c8a034..a084694 100644
--- a/src/github/utils/plugins.ts
+++ b/src/github/utils/plugins.ts
@@ -45,7 +45,7 @@ async function fetchWorkerManifest(url: string): Promise<Manifest | null> {
   if (_manifestCache[url]) {
     return _manifestCache[url];
   }
-  const manifestUrl = `${url}/manifest`;
+  const manifestUrl = `${url}/manifest.json`;
   try {
     const result = await fetch(manifestUrl);
     const manifest = decodeManifest(await result.json());
diff --git a/tests/events.test.ts b/tests/events.test.ts
index b5f16d7..bf4ee9e 100644
--- a/tests/events.test.ts
+++ b/tests/events.test.ts
@@ -30,7 +30,7 @@ afterAll(() => {
 describe("Event related tests", () => {
   beforeEach(() => {
     server.use(
-      http.get("https://plugin-a.internal/manifest", () =>
+      http.get("https://plugin-a.internal/manifest.json", () =>
         HttpResponse.json({
           name: "plugin",
           commands: {
diff --git a/tests/main.test.ts b/tests/main.test.ts
index 8a3eb7d..3749fa2 100644
--- a/tests/main.test.ts
+++ b/tests/main.test.ts
@@ -37,7 +37,7 @@ afterAll(() => {
 describe("Worker tests", () => {
   beforeEach(() => {
     server.use(
-      http.get("https://plugin-a.internal/manifest", () =>
+      http.get("https://plugin-a.internal/manifest.json", () =>
         HttpResponse.json({
           name: "plugin",
           commands: {