diff --git a/src/rollup/index.ts b/src/rollup/index.ts
index 20d82f14808..1f1e69f3171 100644
--- a/src/rollup/index.ts
+++ b/src/rollup/index.ts
@@ -171,14 +171,16 @@ export default function rollup(rawInputOptions: GenericConfigObject): Promise<Ro
 				// ensure we only do one optimization pass per build
 				let optimized = false;
 
-				function generate(rawOutputOptions: GenericConfigObject, isWrite: boolean) {
-					const outputOptions = normalizeOutputOptions(
+				function getOutputOptions(rawOutputOptions: GenericConfigObject) {
+					return normalizeOutputOptions(
 						inputOptions,
 						rawOutputOptions,
 						chunks.length > 1,
 						graph.pluginDriver
 					);
+				}
 
+				function generate(outputOptions: OutputOptions, isWrite: boolean) {
 					timeStart('GENERATE', 1);
 
 					const assetFileNames = outputOptions.assetFileNames || 'assets/[name]-[hash][extname]';
@@ -282,14 +284,17 @@ export default function rollup(rawInputOptions: GenericConfigObject): Promise<Ro
 				const result: RollupBuild = {
 					cache,
 					generate: <any>((rawOutputOptions: GenericConfigObject) => {
-						const promise = generate(rawOutputOptions, false).then(result => createOutput(result));
+						const promise = generate(getOutputOptions(rawOutputOptions), false).then(result =>
+							createOutput(result)
+						);
 						Object.defineProperty(promise, 'code', throwAsyncGenerateError);
 						Object.defineProperty(promise, 'map', throwAsyncGenerateError);
 						return promise;
 					}),
 					watchFiles: Object.keys(graph.watchFiles),
-					write: <any>((outputOptions: OutputOptions) => {
-						if (!outputOptions || (!outputOptions.dir && !outputOptions.file)) {
+					write: <any>((rawOutputOptions: OutputOptions) => {
+						const outputOptions = getOutputOptions(rawOutputOptions);
+						if (!outputOptions.dir && !outputOptions.file) {
 							error({
 								code: 'MISSING_OPTION',
 								message: 'You must specify "output.file" or "output.dir" for the build.'
diff --git a/test/hooks/index.js b/test/hooks/index.js
index 99234a6b18f..dd26ae632c5 100644
--- a/test/hooks/index.js
+++ b/test/hooks/index.js
@@ -4,6 +4,8 @@ const sander = require('sander');
 const { loader } = require('../utils.js');
 const rollup = require('../../dist/rollup.js');
 
+const TEMP_DIR = path.join(__dirname, 'tmp');
+
 describe('hooks', () => {
 	it('allows to read and modify options in the options hook', () => {
 		return rollup
@@ -61,6 +63,41 @@ describe('hooks', () => {
 			});
 	});
 
+	it('allows to replace file with dir in the outputOptions hook', () => {
+		return rollup
+			.rollup({
+				input: 'input',
+				treeshake: false,
+				plugins: [
+					loader({
+						input: `console.log('input');import('other');`,
+						other: `console.log('other');`
+					}),
+					{
+						outputOptions(options) {
+							const newOptions = Object.assign({}, options, {
+								dir: TEMP_DIR,
+								chunkFileNames: 'chunk.js'
+							});
+							delete newOptions.file;
+							return newOptions;
+						}
+					}
+				]
+			})
+			.then(bundle =>
+				bundle.write({
+					file: path.join(TEMP_DIR, 'bundle.js'),
+					format: 'esm'
+				})
+			)
+			.then(() => {
+				const fileNames = sander.readdirSync(TEMP_DIR).sort();
+				assert.deepStrictEqual(fileNames, ['chunk.js', 'input.js']);
+				return sander.rimraf(TEMP_DIR);
+			});
+	});
+
 	it('supports buildStart and buildEnd hooks', () => {
 		let buildStartCnt = 0;
 		let buildEndCnt = 0;
@@ -213,8 +250,6 @@ describe('hooks', () => {
 	});
 
 	it('passes bundle & output object to ongenerate & onwrite hooks, with deprecation warnings', () => {
-		const file = path.join(__dirname, 'tmp/bundle.js');
-
 		let deprecationCnt = 0;
 
 		return rollup
@@ -251,13 +286,13 @@ describe('hooks', () => {
 			})
 			.then(bundle => {
 				return bundle.write({
-					file,
+					file: path.join(TEMP_DIR, 'bundle.js'),
 					format: 'es'
 				});
 			})
 			.then(() => {
 				assert.equal(deprecationCnt, 2);
-				return sander.unlink(file);
+				return sander.rimraf(TEMP_DIR);
 			});
 	});
 
@@ -289,7 +324,7 @@ describe('hooks', () => {
 
 	it('calls onwrite hooks in sequence', () => {
 		const result = [];
-		const file = path.join(__dirname, 'tmp/bundle.js');
+		const file = path.join(TEMP_DIR, 'bundle.js');
 
 		return rollup
 			.rollup({
@@ -321,8 +356,7 @@ describe('hooks', () => {
 			})
 			.then(() => {
 				assert.deepEqual(result, [{ a: file, format: 'cjs' }, { b: file, format: 'cjs' }]);
-
-				return sander.unlink(file);
+				return sander.rimraf(TEMP_DIR);
 			});
 	});
 
@@ -863,7 +897,7 @@ module.exports = input;
 	});
 
 	it('supports writeBundle hook', () => {
-		const file = path.join(__dirname, 'tmp/bundle.js');
+		const file = path.join(TEMP_DIR, 'bundle.js');
 		let bundle;
 		let callCount = 0;
 		return rollup
@@ -889,7 +923,10 @@ module.exports = input;
 				]
 			})
 			.then(bundle => bundle.write({ format: 'esm', file }))
-			.then(() => assert.strictEqual(callCount, 1));
+			.then(() => {
+				assert.strictEqual(callCount, 1);
+				return sander.rimraf(TEMP_DIR);
+			});
 	});
 
 	it('supports this.cache for plugins', () => {
@@ -1227,6 +1264,9 @@ module.exports = input;
 					'this.watcher usage is deprecated in plugins. Use the watchChange plugin hook and this.addWatchFile() instead.'
 				);
 			},
+			output: {
+				format: 'esm'
+			},
 			plugins: [
 				loader({ input: `alert('hello')` }),
 				{
diff --git a/test/misc/write-bundle.js b/test/misc/write-bundle.js
index 9a14204457f..1ef523fe9cc 100644
--- a/test/misc/write-bundle.js
+++ b/test/misc/write-bundle.js
@@ -21,10 +21,10 @@ describe('bundle.write()', () => {
 			.then(bundle => {
 				assert.throws(() => {
 					bundle.write();
-				}, /You must specify "output\.file"/);
+				}, /You must supply an options object/);
 
 				assert.throws(() => {
-					bundle.write({});
+					bundle.write({format: 'esm'});
 				}, /You must specify "output\.file"/);
 			});
 	});