diff --git a/docs/README.md b/docs/README.md
index 247877ee..0d489270 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -7,6 +7,7 @@ Delightful library bundler.
 - 🚀 Fast, zero-config by default.
 - 📦 Using Rollup under the hood.
 - 🚗 Automatically transforms JS files using Buble, Babel or TypeScript.
+- 🧩 Bundles TypeScript declarations into a single `.d.ts` file.
 - 💅 Built-in support for CSS, Sass, Stylus, Less and CSS modules.
 - 🎶 Ridiculously easy to use Rollup plugins if you want.
 - 🚨 Friendly error logging experience.
@@ -35,3 +36,9 @@ And you want minified bundles?
 ```bash
 bili --format esm-min --format cjs-min
 ```
+
+Bundle TypeScript declarations too:
+
+```bash
+bili src/index.ts --dts
+```
diff --git a/docs/recipes/javascript.md b/docs/recipes/javascript.md
index 466640c7..1b271cb2 100644
--- a/docs/recipes/javascript.md
+++ b/docs/recipes/javascript.md
@@ -22,7 +22,7 @@ module.exports = {
   presets: ['bili/babel'],
   plugins: [
     // Add your babel plugins...
-  ]
+  ],
 }
 ```
 
@@ -53,6 +53,23 @@ We automatically use [rollup-plugin-typescript2](https://github.com/ezolenko/rol
 yarn add typescript rollup-plugin-typescript2 --dev
 ```
 
+Bili can also bundle emitted declarations into one `.d.ts` entry file:
+
+```bash
+bili src/index.ts --dts
+```
+
+Or choose the declaration bundle file name:
+
+```js
+// bili.config.js
+module.exports = {
+  output: {
+    dts: 'index.d.ts',
+  },
+}
+```
+
 ## Use Babel with TypeScript
 
 By default Babel is also used for `.ts` files, it will process the file after TypeScript. It's recommended to set `compilerOptions.target` to `es2017` or above in `tsconfig.json` and let Babel transform the code to ES5 instead. If you want to disable Babel, set `plugins: { babel: false }` in your Bili config file.
diff --git a/package.json b/package.json
index 9ca6d5ed..fc6d69d4 100644
--- a/package.json
+++ b/package.json
@@ -48,6 +48,7 @@
     "chalk": "^4.1.0",
     "ora": "^4.0.4",
     "rollup": "^2.16.1",
+    "rollup-plugin-dts": "1.3.0",
     "rollup-plugin-hashbang": "^2.2.2",
     "rollup-plugin-postcss": "^3.1.2",
     "rollup-plugin-terser": "^6.1.0",
diff --git a/src/cli.ts b/src/cli.ts
index 6a13a725..8fa7e851 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -47,6 +47,10 @@ cli
     '--no-map',
     'Disable source maps, enabled by default for minified bundles'
   )
+  .option(
+    '--dts [fileName]',
+    'Bundle TypeScript declarations into a single .d.ts file'
+  )
   .option('--map-exclude-sources', 'Exclude source code in source maps')
   .option('--no-async-pro, --no-async-to-promises', 'Leave async/await as is')
   .option('--concurrent', 'Build concurrently')
@@ -70,6 +74,7 @@ cli
           minify: options.minify,
           extractCSS: options.extractCss,
           sourceMap: options.map,
+          dts: options.dts,
           sourceMapExcludeSources: options.mapExcludeSources,
           target: options.target,
         },
diff --git a/src/index.ts b/src/index.ts
index 2121a089..7b3ddc7f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,5 +1,6 @@
 import './polyfills'
 import path from 'path'
+import fs from 'fs'
 import colors from 'chalk'
 import prettyBytes from 'pretty-bytes'
 import formatTime from 'pretty-ms'
@@ -7,6 +8,7 @@ import textTable from 'text-table'
 import resolveFrom from 'resolve-from'
 import boxen from 'boxen'
 import stringWidth from 'string-width'
+import dts from 'rollup-plugin-dts'
 import {
   rollup,
   watch,
@@ -61,6 +63,7 @@ interface RollupConfigInput {
 
 type PluginFactory = (opts: any) => RollupPlugin
 type GetPlugin = (name: string) => Promise<PluginFactory>
+type SourceMeta = RollupConfigInput['source']
 
 export class Bundler {
   rootDir: string
@@ -198,6 +201,17 @@ export class Bundler {
       }
     }
 
+    const typescriptCompilerOptions: { [key: string]: any } = {
+      module: 'esnext',
+    }
+    const tsconfig = path.join(this.rootDir, 'tsconfig.json')
+    if (config.output.dts) {
+      Object.assign(typescriptCompilerOptions, {
+        declaration: true,
+        declarationMap: false,
+      })
+    }
+
     const pluginsOptions: { [key: string]: any } = {
       progress:
         config.plugins.progress !== false &&
@@ -248,11 +262,11 @@ export class Bundler {
         (source.hasTs || config.plugins.typescript2) &&
         merge(
           {
+            cwd: this.rootDir,
+            ...(fs.existsSync(tsconfig) && { tsconfig }),
             objectHashIgnoreUnknownHack: getObjectHashIgnoreUnknownHack(),
             tsconfigOverride: {
-              compilerOptions: {
-                module: 'esnext',
-              },
+              compilerOptions: typescriptCompilerOptions,
             },
           },
           config.plugins.typescript2
@@ -463,8 +477,8 @@ export class Bundler {
       // Since we only output to `.js` now
       // Probably remove it in the future
       .replace(/\[ext\]/, '.js')
- 
-    if (rollupFormat === 'esm')  {
+
+    if (rollupFormat === 'esm') {
       fileName = fileName.replace(/\[format\]/, 'esm')
     }
 
@@ -567,6 +581,14 @@ export class Bundler {
         ...getMeta(files),
       }
     })
+    const declarationSources = sources.filter(
+      (source) => source.hasTs && this.config.output.dts
+    )
+    const existingDeclarationFiles = new Set(
+      declarationSources.length > 0
+        ? findDeclarationFiles(path.resolve(this.config.output.dir || 'dist'))
+        : []
+    )
 
     let { format, target } = this.config.output
     if (Array.isArray(format)) {
@@ -649,6 +671,14 @@ export class Bundler {
             context
           )
         }
+        if (options.write && declarationSources.length > 0) {
+          await waterfall(
+            declarationSources.map((source) => () => {
+              return this.buildDtsBundle(source, existingDeclarationFiles)
+            }),
+            context
+          )
+        }
       } catch (err) {
         spinner.stop()
         throw err
@@ -678,6 +708,141 @@ export class Bundler {
     }
   }
 
+  async buildDtsBundle(
+    source: SourceMeta,
+    existingDeclarationFiles = new Set<string>()
+  ) {
+    const outputDir = path.resolve(this.config.output.dir || 'dist')
+    this.emitDtsFiles(source, outputDir)
+    const sourceFile = getSingleDeclarationSource(source)
+    const inputFile = findDeclarationFile(outputDir, sourceFile)
+    if (!inputFile) {
+      throw new Error(`Declaration file for "${sourceFile}" was not emitted`)
+    }
+
+    const outputFile = path.resolve(
+      outputDir,
+      getDtsFileName(this.config.output.dts, sourceFile)
+    )
+    const tempFile = `${outputFile}.tmp`
+    const declarationFiles = findDeclarationFiles(outputDir).filter(
+      (file) =>
+        !existingDeclarationFiles.has(file) &&
+        file !== outputFile &&
+        file !== tempFile
+    )
+    const bundle = await rollup({
+      input: inputFile,
+      plugins: [dts()],
+    })
+    await bundle.write({
+      file: tempFile,
+      format: 'es',
+    })
+    fs.renameSync(tempFile, outputFile)
+    for (const file of declarationFiles) {
+      fs.unlinkSync(file)
+    }
+
+    const relative = path.relative(process.cwd(), outputFile)
+    const assets: Assets = new Map()
+    assets.set(relative, {
+      absolute: outputFile,
+      get source() {
+        return fs.readFileSync(outputFile, 'utf8')
+      },
+    })
+    this.bundles.add(assets)
+    await printAssets(assets, 'Bundled declaration')
+  }
+
+  emitDtsFiles(source: SourceMeta, outputDir: string) {
+    const ts = this.localRequire('typescript')
+    const tsconfig = path.join(this.rootDir, 'tsconfig.json')
+    let compilerOptions: { [key: string]: any } = {}
+    if (fs.existsSync(tsconfig)) {
+      const tsconfigJson = ts.readConfigFile(tsconfig, ts.sys.readFile)
+      if (tsconfigJson.error) {
+        throw new Error(
+          formatTsDiagnostics(ts, [tsconfigJson.error], this.rootDir)
+        )
+      }
+      const parsedTsconfig = ts.parseJsonConfigFileContent(
+        tsconfigJson.config,
+        ts.sys,
+        this.rootDir
+      )
+      if (parsedTsconfig.errors.length > 0) {
+        throw new Error(
+          formatTsDiagnostics(ts, parsedTsconfig.errors, this.rootDir)
+        )
+      }
+      compilerOptions = parsedTsconfig.options
+    }
+
+    compilerOptions = {
+      ...compilerOptions,
+      declaration: true,
+      declarationDir: outputDir,
+      declarationMap: false,
+      module:
+        compilerOptions.module === undefined
+          ? ts.ModuleKind.ESNext
+          : compilerOptions.module,
+      moduleResolution:
+        compilerOptions.moduleResolution === undefined
+          ? ts.ModuleResolutionKind.NodeJs
+          : compilerOptions.moduleResolution,
+      noEmit: false,
+      noEmitOnError: false,
+      outDir: outputDir,
+      skipLibCheck:
+        compilerOptions.skipLibCheck === undefined
+          ? true
+          : compilerOptions.skipLibCheck,
+      target:
+        compilerOptions.target === undefined
+          ? ts.ScriptTarget.ES2017
+          : compilerOptions.target,
+      types: compilerOptions.types === undefined ? [] : compilerOptions.types,
+    }
+
+    const program = ts.createProgram(
+      [
+        this.resolveRootDir(
+          stripRelativePrefix(getSingleDeclarationSource(source))
+        ),
+      ],
+      compilerOptions
+    )
+    const diagnostics = ts
+      .getPreEmitDiagnostics(program)
+      .filter((diagnostic: any) => {
+        return diagnostic.category === ts.DiagnosticCategory.Error
+      })
+    if (diagnostics.length > 0) {
+      throw new Error(formatTsDiagnostics(ts, diagnostics, this.rootDir))
+    }
+
+    const result = program.emit(
+      undefined,
+      (fileName: string, content: string) => {
+        if (!fileName.endsWith('.d.ts')) {
+          return
+        }
+        ensureDir(path.dirname(fileName))
+        fs.writeFileSync(fileName, content)
+      },
+      undefined,
+      false
+    )
+    if (result.emitSkipped) {
+      throw new Error(
+        formatTsDiagnostics(ts, result.diagnostics || [], this.rootDir)
+      )
+    }
+  }
+
   handleError(err: any) {
     if (err.stack) {
       console.error()
@@ -740,4 +905,84 @@ function getDefaultFileName(format: RollupFormat) {
   return format === 'cjs' ? `[name][min][ext]` : `[name].[format][min][ext]`
 }
 
+function getSingleDeclarationSource(source: SourceMeta) {
+  if (Array.isArray(source.input)) {
+    if (source.input.length !== 1) {
+      throw new Error('output.dts requires a single TypeScript entry')
+    }
+    return source.input[0]
+  }
+
+  const values = Object.values(source.input)
+  if (values.length !== 1) {
+    throw new Error('output.dts requires a single TypeScript entry')
+  }
+  return values[0]
+}
+
+function getDtsFileName(
+  dtsOption: boolean | string | undefined,
+  sourceFile: string
+) {
+  if (typeof dtsOption === 'string') {
+    return dtsOption.endsWith('.d.ts') ? dtsOption : `${dtsOption}.d.ts`
+  }
+  return `${path.basename(sourceFile).replace(/\.[cm]?[jt]sx?$/, '')}.d.ts`
+}
+
+function stripRelativePrefix(file: string) {
+  return file.replace(/^\.\//, '')
+}
+
+function findDeclarationFile(outputDir: string, sourceFile: string) {
+  const fileName = getDtsFileName(true, sourceFile)
+  const direct = path.resolve(outputDir, fileName)
+  if (fs.existsSync(direct)) {
+    return direct
+  }
+
+  return findDeclarationFiles(outputDir).find(
+    (file) => path.basename(file) === fileName
+  )
+}
+
+function findDeclarationFiles(dir: string): string[] {
+  if (!fs.existsSync(dir)) {
+    return []
+  }
+
+  return fs.readdirSync(dir).reduce((files: string[], name) => {
+    const file = path.join(dir, name)
+    if (fs.statSync(file).isDirectory()) {
+      return files.concat(findDeclarationFiles(file))
+    }
+    if (file.endsWith('.d.ts')) {
+      files.push(file)
+    }
+    return files
+  }, [])
+}
+
+function ensureDir(dir: string) {
+  if (fs.existsSync(dir)) {
+    return
+  }
+  const parent = path.dirname(dir)
+  if (parent !== dir) {
+    ensureDir(parent)
+  }
+  fs.mkdirSync(dir)
+}
+
+function formatTsDiagnostics(ts: any, diagnostics: any[], rootDir: string) {
+  if (diagnostics.length === 0) {
+    return 'TypeScript declaration emit failed'
+  }
+  return ts.formatDiagnosticsWithColorAndContext(diagnostics, {
+    getCanonicalFileName: (fileName: string) => fileName,
+    getCurrentDirectory: () => rootDir,
+    getNewLine: () => '\n',
+  })
+}
+
 export { Config, NormalizedConfig, Options, ConfigOutput }
diff --git a/src/types.ts b/src/types.ts
index dcca8edd..0c25a5f8 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -2,7 +2,7 @@ import {
   ModuleFormat as RollupFormat,
   InputOptions,
   OutputOptions,
-  Plugin as RollupPlugin
+  Plugin as RollupPlugin,
 } from 'rollup'
 
 import { Banner } from './utils/get-banner'
@@ -157,6 +157,14 @@ export interface ConfigOutput {
    * @default `true` for minified bundle, `false` otherwise
    */
   sourceMap?: boolean
+  /**
+   * Bundle TypeScript declaration output into a single `.d.ts` file.
+   *
+   * Set to `true` to use the input basename, or pass a file name.
+   *
+   * @cli `--dts [fileName]`
+   */
+  dts?: boolean | string
   /**
    * Exclude source code in source maps
    */
diff --git a/test/__snapshots__/index.test.ts.snap b/test/__snapshots__/index.test.ts.snap
index 727dc002..c33ed2f6 100644
--- a/test/__snapshots__/index.test.ts.snap
+++ b/test/__snapshots__/index.test.ts.snap
@@ -196,6 +196,16 @@ module.exports = index;
 "
 `;
 
+exports[`dts bundle 1`] = `
+"interface Message {
+    value: string;
+}
+declare function createMessage(value: string): Message;
+
+export { Message, createMessage };
+"
+`;
+
 exports[`exclude file: exclude file dist/index.js 1`] = `
 "'use strict';
 
diff --git a/test/fixtures/declaration-bundle/index.ts b/test/fixtures/declaration-bundle/index.ts
new file mode 100644
index 00000000..029ffe3a
--- /dev/null
+++ b/test/fixtures/declaration-bundle/index.ts
@@ -0,0 +1 @@
+export { createMessage, Message } from './message'
diff --git a/test/fixtures/declaration-bundle/message.ts b/test/fixtures/declaration-bundle/message.ts
new file mode 100644
index 00000000..da0c227d
--- /dev/null
+++ b/test/fixtures/declaration-bundle/message.ts
@@ -0,0 +1,7 @@
+export interface Message {
+  value: string
+}
+
+export function createMessage(value: string): Message {
+  return { value }
+}
diff --git a/test/fixtures/declaration-bundle/tsconfig.json b/test/fixtures/declaration-bundle/tsconfig.json
new file mode 100644
index 00000000..87d56766
--- /dev/null
+++ b/test/fixtures/declaration-bundle/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "compilerOptions": {
+    "target": "es2017",
+    "module": "esnext",
+    "moduleResolution": "node",
+    "strict": true
+  },
+  "include": ["*.ts"]
+}
diff --git a/test/index.test.ts b/test/index.test.ts
index 1e281a15..13c66cfa 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -1,4 +1,5 @@
 import path from 'path'
+import fs from 'fs'
 import { Bundler, Config, Options } from '../src'
 
 process.env.BABEL_ENV = 'anything-not-test'
@@ -7,20 +8,35 @@ function fixture(...args: string[]) {
   return path.join(__dirname, 'fixtures', ...args)
 }
 
-function generate(config: Config, options: Options) {
+function removeDir(dir: string) {
+  if (!fs.existsSync(dir)) {
+    return
+  }
+  for (const name of fs.readdirSync(dir)) {
+    const file = path.join(dir, name)
+    if (fs.statSync(file).isDirectory()) {
+      removeDir(file)
+    } else {
+      fs.unlinkSync(file)
+    }
+  }
+  fs.rmdirSync(dir)
+}
+
+function generate(config: Config, options: Options, runOptions: any = {}) {
   const bundler = new Bundler(config, {
     logLevel: 'quiet',
     configFile: false,
-    ...options
+    ...options,
   })
-  return bundler.run()
+  return bundler.run(runOptions)
 }
 
 function snapshot(
   {
     title,
     input,
-    cwd
+    cwd,
   }: { title: string; input: string | string[]; cwd?: string },
   config?: Config
 ) {
@@ -28,10 +44,10 @@ function snapshot(
     const { bundles } = await generate(
       {
         input,
-        ...config
+        ...config,
       },
       {
-        rootDir: cwd
+        rootDir: cwd,
       }
     )
     for (const bundle of bundles) {
@@ -46,17 +62,17 @@ function snapshot(
 snapshot({
   title: 'defaults',
   input: 'index.js',
-  cwd: fixture('defaults')
+  cwd: fixture('defaults'),
 })
 
 snapshot(
   {
     title: 'banner:true default',
     input: 'index.js',
-    cwd: fixture('banner/default')
+    cwd: fixture('banner/default'),
   },
   {
-    banner: true
+    banner: true,
   }
 )
 
@@ -64,15 +80,15 @@ snapshot(
   {
     title: 'banner:object',
     input: 'default.js',
-    cwd: fixture()
+    cwd: fixture(),
   },
   {
     banner: {
       author: 'author',
       license: 'GPL',
       name: 'name',
-      version: '1.2.3'
-    }
+      version: '1.2.3',
+    },
   }
 )
 
@@ -80,10 +96,10 @@ snapshot(
   {
     title: 'banner:string',
     input: 'default.js',
-    cwd: fixture()
+    cwd: fixture(),
   },
   {
-    banner: 'woot'
+    banner: 'woot',
   }
 )
 
@@ -91,10 +107,10 @@ snapshot(
   {
     title: 'exclude file',
     input: 'index.js',
-    cwd: fixture('exclude-file')
+    cwd: fixture('exclude-file'),
   },
   {
-    externals: ['./foo.js']
+    externals: ['./foo.js'],
   }
 )
 
@@ -102,11 +118,11 @@ snapshot(
   {
     title: 'extendOptions',
     input: ['foo.js', 'bar.js'],
-    cwd: fixture('extend-options')
+    cwd: fixture('extend-options'),
   },
   {
     output: {
-      format: ['umd', 'umd-min', 'cjs']
+      format: ['umd', 'umd-min', 'cjs'],
     },
     extendConfig(config, { format }) {
       if (format === 'umd') {
@@ -116,7 +132,7 @@ snapshot(
         config.output.moduleName = 'min'
       }
       return config
-    }
+    },
   }
 )
 
@@ -124,54 +140,54 @@ snapshot(
   {
     title: 'bundle-node-modules',
     input: 'index.js',
-    cwd: fixture('bundle-node-modules')
+    cwd: fixture('bundle-node-modules'),
   },
   {
-    bundleNodeModules: true
+    bundleNodeModules: true,
   }
 )
 
 snapshot({
   title: 'async',
   input: 'index.js',
-  cwd: fixture('async')
+  cwd: fixture('async'),
 })
 
 snapshot({
   title: 'babel:with-config',
   input: 'index.js',
-  cwd: fixture('babel/with-config')
+  cwd: fixture('babel/with-config'),
 })
 
 snapshot(
   {
     title: 'babel:disable-config',
     input: 'index.js',
-    cwd: fixture('babel/with-config')
+    cwd: fixture('babel/with-config'),
   },
   {
     babel: {
-      babelrc: false
-    }
+      babelrc: false,
+    },
   }
 )
 
 snapshot({
   title: 'babel:object-rest-spread',
   input: 'index.js',
-  cwd: fixture('babel/object-rest-spread')
+  cwd: fixture('babel/object-rest-spread'),
 })
 
 snapshot(
   {
     title: 'uglify',
     input: 'index.js',
-    cwd: fixture('uglify')
+    cwd: fixture('uglify'),
   },
   {
     output: {
-      format: 'cjs-min'
-    }
+      format: 'cjs-min',
+    },
   }
 )
 
@@ -179,37 +195,65 @@ snapshot(
   {
     title: 'inline-certain-modules',
     input: 'index.js',
-    cwd: fixture('inline-certain-modules')
+    cwd: fixture('inline-certain-modules'),
   },
   {
-    bundleNodeModules: ['fake-module']
+    bundleNodeModules: ['fake-module'],
   }
 )
 
 snapshot({
   title: 'vue plugin',
   input: 'component.vue',
-  cwd: fixture('vue')
+  cwd: fixture('vue'),
 })
 
 snapshot({
   title: 'Typescript',
   input: 'index.ts',
-  cwd: fixture('typescript')
+  cwd: fixture('typescript'),
 })
 
+test('dts bundle', async () => {
+  const cwd = fixture('declaration-bundle')
+  const dist = path.join(cwd, 'dist')
+  removeDir(dist)
+  await generate(
+    {
+      input: 'index.ts',
+      output: {
+        dir: dist,
+        dts: true,
+      },
+      resolvePlugins: {
+        typescript2: require('rollup-plugin-typescript2'),
+      },
+    },
+    {
+      rootDir: cwd,
+    },
+    {
+      write: true,
+    }
+  )
+  expect(fs.existsSync(path.join(dist, 'message.d.ts'))).toBe(false)
+  expect(
+    fs.readFileSync(path.join(dist, 'index.d.ts'), 'utf8')
+  ).toMatchSnapshot()
+}, 20000)
+
 snapshot(
   {
     title: 'custom rollup plugin',
     input: 'index.js',
-    cwd: fixture('custom-rollup-plugin')
+    cwd: fixture('custom-rollup-plugin'),
   },
   {
     plugins: {
       strip: {
-        functions: ['console.log']
-      }
-    }
+        functions: ['console.log'],
+      },
+    },
   }
 )
 
@@ -217,14 +261,14 @@ snapshot(
   {
     title: 'custom scoped rollup plugin',
     input: 'index.js',
-    cwd: fixture('custom-scoped-rollup-plugin')
+    cwd: fixture('custom-scoped-rollup-plugin'),
   },
   {
     plugins: {
       '@rollup/plugin-strip': {
-        functions: ['console.log']
-      }
-    }
+        functions: ['console.log'],
+      },
+    },
   }
 )
 
@@ -232,14 +276,14 @@ snapshot(
   {
     title: '`@rollup/plugin-replace` can accepts custom options',
     input: 'index.js',
-    cwd: fixture('custom-scoped-rollup-plugin/replace')
+    cwd: fixture('custom-scoped-rollup-plugin/replace'),
   },
   {
     plugins: {
       replace: {
-        'process.env.NODE_ENV': JSON.stringify('production')
-      }
-    }
+        'process.env.NODE_ENV': JSON.stringify('production'),
+      },
+    },
   }
 )
 
@@ -247,12 +291,12 @@ snapshot(
   {
     title: 'target:browser',
     input: 'index.js',
-    cwd: fixture('target/browser')
+    cwd: fixture('target/browser'),
   },
   {
     output: {
-      target: 'browser'
-    }
+      target: 'browser',
+    },
   }
 )
 
@@ -260,13 +304,13 @@ snapshot(
   {
     title: 'umd and iife should drop process.env.NODE_ENV',
     input: 'index.js',
-    cwd: fixture('format')
+    cwd: fixture('format'),
   },
   {
     output: {
       format: ['umd', 'umd-min', 'iife', 'iife-min'],
-      moduleName: 'dropNodeEnv'
-    }
+      moduleName: 'dropNodeEnv',
+    },
   }
 )
 
@@ -274,13 +318,13 @@ snapshot(
   {
     title: 'umd and iife should preserve existing env.NODE_ENV',
     input: 'index.js',
-    cwd: fixture('format')
+    cwd: fixture('format'),
   },
   {
     output: {
       format: ['umd', 'umd-min', 'iife', 'iife-min'],
-      moduleName: 'dropNodeEnv'
+      moduleName: 'dropNodeEnv',
     },
-    env: { NODE_ENV: 'production' }
+    env: { NODE_ENV: 'production' },
   }
 )
diff --git a/yarn.lock b/yarn.lock
index 96fb332d..5c70e670 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -9076,6 +9076,13 @@ rimraf@^3.0.0:
   dependencies:
     glob "^7.1.3"
 
+rollup-plugin-dts@1.3.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/rollup-plugin-dts/-/rollup-plugin-dts-1.3.0.tgz#34de28ea8c9464392f2b0d4cb8cd0fe7c51d482e"
+  integrity sha512-G08HZvwliQdRbAOwNb1VnyKuRSp1EXpKPW5FrvRcHbxsmPP2Co443zZ0p8tSCTjuC5xNYyZ9VMzjcwtqrPn6Ew==
+  optionalDependencies:
+    "@babel/code-frame" "^7.8.3"
+
 rollup-plugin-hashbang@^2.2.2:
   version "2.2.2"
   resolved "https://registry.npmjs.org/rollup-plugin-hashbang/-/rollup-plugin-hashbang-2.2.2.tgz#971fc49b452e63f9dfdc75f79ae7256b3485e750"