diff --git a/src/rollup/index.ts b/src/rollup/index.ts
index a2e1a8ae119..b69c1f135e7 100644
--- a/src/rollup/index.ts
+++ b/src/rollup/index.ts
@@ -321,7 +321,9 @@ export default function rollup(
 					generate: <any>((rawOutputOptions: GenericConfigObject) => {
 						const promise = generate(rawOutputOptions, false).then(
 							result =>
-								inputOptions.experimentalCodeSplitting ? result : <OutputChunk>result[chunks[0].id]
+								inputOptions.experimentalCodeSplitting
+									? { output: result }
+									: <OutputChunk>result[chunks[0].id]
 						);
 						Object.defineProperty(promise, 'code', throwAsyncGenerateError);
 						Object.defineProperty(promise, 'map', throwAsyncGenerateError);
@@ -353,7 +355,7 @@ export default function rollup(
 							).then(
 								() =>
 									inputOptions.experimentalCodeSplitting
-										? result
+										? { output: result }
 										: <OutputChunk>result[chunks[0].id]
 							)
 						);
diff --git a/src/rollup/types.d.ts b/src/rollup/types.d.ts
index 4055a6c3551..26fe43558b8 100644
--- a/src/rollup/types.d.ts
+++ b/src/rollup/types.d.ts
@@ -344,8 +344,8 @@ export interface OutputBundle {
 
 export interface RollupBuild {
 	cache: RollupCache;
-	generate: (outputOptions: OutputOptions) => Promise<OutputBundle>;
-	write: (options: OutputOptions) => Promise<OutputBundle>;
+	generate: (outputOptions: OutputOptions) => Promise<{ output: OutputBundle }>;
+	write: (options: OutputOptions) => Promise<{ output: OutputBundle }>;
 	getTimings?: () => SerializedTimings;
 }
 
diff --git a/test/hooks/index.js b/test/hooks/index.js
index 716d2ad54a3..d88b85463b9 100644
--- a/test/hooks/index.js
+++ b/test/hooks/index.js
@@ -267,9 +267,9 @@ describe('hooks', () => {
 			.then(bundle => {
 				return bundle.generate({ format: 'es' });
 			})
-			.then(outputBundle => {
-				assert.equal(outputBundle['assets/test-19916f7d.ext'], 'hello world');
-				assert.equal(outputBundle['input.js'].code, `var input = new URL(\'../assets/test-19916f7d.ext\', import.meta.url).href;\n\nexport default input;\n`);
+			.then(({ output }) => {
+				assert.equal(output['assets/test-19916f7d.ext'], 'hello world');
+				assert.equal(output['input.js'].code, `var input = new URL(\'../assets/test-19916f7d.ext\', import.meta.url).href;\n\nexport default input;\n`);
 			});
 	});
 
@@ -291,8 +291,8 @@ describe('hooks', () => {
 			.then(bundle => {
 				return bundle.generate({ format: 'cjs' });
 			})
-			.then(outputBundle => {
-				assert.equal(outputBundle['input.js'].code, `'use strict';
+			.then(({ output }) => {
+				assert.equal(output['input.js'].code, `'use strict';
 
 var input = new (typeof URL !== 'undefined' ? URL : require('ur'+'l').URL)((process.browser ? '' : 'file:') + __dirname + '/assets/test-19916f7d.ext', process.browser && document.baseURI).href;
 
@@ -322,8 +322,8 @@ module.exports = input;
 					assetFileNames: '[name][extname]'
 				});
 			})
-			.then(outputBundle => {
-				assert.equal(outputBundle['test.ext'], 'hello world');
+			.then(({ output }) => {
+				assert.equal(output['test.ext'], 'hello world');
 			});
 	});
 
@@ -349,8 +349,8 @@ module.exports = input;
 			.then(bundle => {
 				return bundle.generate({ format: 'es' });
 			})
-			.then(outputBundle => {
-				assert.equal(outputBundle['assets/test-19916f7d.ext'], 'hello world');
+			.then(({ output }) => {
+				assert.equal(output['assets/test-19916f7d.ext'], 'hello world');
 			});
 	});
 
@@ -380,8 +380,8 @@ module.exports = input;
 			.then(bundle => {
 				return bundle.generate({ format: 'es' });
 			})
-			.then(outputBundle => {
-				assert.equal(outputBundle['assets/test-19916f7d.ext'], 'hello world');
+			.then(({ output }) => {
+				assert.equal(output['assets/test-19916f7d.ext'], 'hello world');
 			});
 	});
 
@@ -503,16 +503,16 @@ module.exports = input;
 					.then(outputBundle2 => [outputBundle1, outputBundle2])
 				)
 			)
-			.then(([outputBundle1, outputBundle2]) => {
-				assert.equal(outputBundle1['input.js'].code, `alert('hello');\n`);
-				assert.equal(outputBundle1['assets/lateDepAsset-671f747d'], `custom source`);
-				assert.equal(outputBundle1['assets/lateMainAsset-863ea4b5'], `references assets/lateDepAsset-671f747d`);
-
-				assert.equal(outputBundle2['input.js'].code, `'use strict';\n\nalert('hello');\n`);
-				assert.equal(outputBundle2['assets/lateDepAsset-671f747d'], undefined);
-				assert.equal(outputBundle2['assets/lateMainAsset-863ea4b5'], undefined);
-				assert.equal(outputBundle2['assets/lateDepAsset-c107f5fc'], `different source`);
-				assert.equal(outputBundle2['assets/lateMainAsset-6dc2262b'], `references assets/lateDepAsset-c107f5fc`);
+			.then(([{ output: output1 }, { output: output2 }]) => {
+				assert.equal(output1['input.js'].code, `alert('hello');\n`);
+				assert.equal(output1['assets/lateDepAsset-671f747d'], `custom source`);
+				assert.equal(output1['assets/lateMainAsset-863ea4b5'], `references assets/lateDepAsset-671f747d`);
+
+				assert.equal(output2['input.js'].code, `'use strict';\n\nalert('hello');\n`);
+				assert.equal(output2['assets/lateDepAsset-671f747d'], undefined);
+				assert.equal(output2['assets/lateMainAsset-863ea4b5'], undefined);
+				assert.equal(output2['assets/lateDepAsset-c107f5fc'], `different source`);
+				assert.equal(output2['assets/lateMainAsset-6dc2262b'], `references assets/lateDepAsset-c107f5fc`);
 			});
 	});