diff --git a/build/index.js b/build/index.js
index 4dd7708c2..76b602777 100644
--- a/build/index.js
+++ b/build/index.js
@@ -57,7 +57,7 @@ async function listLocaleJson(localeArr) {
       }))
     }
 
-    build(configFactory({
+    await build(configFactory({
       input: './src/index.js',
       fileName: './dayjs.min.js'
     }))
diff --git a/test/build/mainBuildAwait.test.js b/test/build/mainBuildAwait.test.js
new file mode 100644
index 000000000..55e861fa1
--- /dev/null
+++ b/test/build/mainBuildAwait.test.js
@@ -0,0 +1,44 @@
+describe('main bundle build ordering', () => {
+  beforeEach(() => {
+    jest.resetModules()
+  })
+
+  afterEach(() => {
+    jest.restoreAllMocks()
+  })
+
+  it('finishes the main Rollup build before writing the locale manifest', async () => {
+    let resolveRollup
+    let resolveManifest
+    const manifestWritten = new Promise((resolve) => {
+      resolveManifest = resolve
+    })
+    const writeFile = jest.fn((file, contents, encoding, callback) => {
+      callback()
+      resolveManifest()
+    })
+
+    jest.doMock('rollup', () => ({
+      rollup: () => new Promise((resolve) => {
+        resolveRollup = () => resolve({ write: () => Promise.resolve() })
+      })
+    }))
+    jest.doMock('../../build/rollup.config', () => config => config)
+    jest.doMock('ncp', () => ({ ncp: (source, destination, callback) => callback() }))
+    jest.doMock('fs', () => ({
+      readdir: (directory, callback) => callback(null, []),
+      readFile: (file, encoding, callback) => callback(null, ''),
+      writeFile
+    }))
+
+    require('../../build') // eslint-disable-line global-require
+
+    await new Promise(resolve => setImmediate(resolve))
+    expect(resolveRollup).toEqual(expect.any(Function))
+    expect(writeFile).not.toHaveBeenCalled()
+
+    resolveRollup()
+    await manifestWritten
+    expect(writeFile).toHaveBeenCalledTimes(1)
+  })
+})