diff --git a/packages/plugin-app-duration/package.json b/packages/plugin-app-duration/package.json
index 795268d42e..c00b48ebd1 100644
--- a/packages/plugin-app-duration/package.json
+++ b/packages/plugin-app-duration/package.json
@@ -1,7 +1,15 @@
 {
   "name": "@bugsnag/plugin-app-duration",
   "version": "8.0.0",
-  "main": "app.js",
+  "main": "dist/app-duration.js",
+  "types": "dist/types/app-duration.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/types/app-duration.d.ts",
+      "default": "./dist/app-duration.js",
+      "import": "./dist/app-duration.mjs"
+    }
+  },
   "description": "@bugsnag/js plugin to set app duration in browsers and node",
   "homepage": "https://www.bugsnag.com/",
   "repository": {
@@ -21,5 +29,10 @@
   },
   "peerDependencies": {
     "@bugsnag/core": "^8.0.0"
+  },
+  "scripts": {
+    "build": "npm run build:npm",
+    "build:npm": "rollup --config rollup.config.npm.mjs",
+    "clean": "rm -rf dist/*"
   }
 }
diff --git a/packages/plugin-app-duration/rollup.config.npm.mjs b/packages/plugin-app-duration/rollup.config.npm.mjs
new file mode 100644
index 0000000000..328994acc2
--- /dev/null
+++ b/packages/plugin-app-duration/rollup.config.npm.mjs
@@ -0,0 +1,25 @@
+import createRollupConfig from '../../.rollup/index.mjs'
+
+export default createRollupConfig({
+    input: 'src/app-duration.ts',
+    output: [
+        {
+            dir: `dist`,
+            entryFileNames: '[name].js',
+            format: 'cjs',
+            preserveModules: true,
+            generatedCode: {
+              preset: 'es2015',
+            }
+        },
+        {
+            dir: `dist`,
+            entryFileNames: '[name].mjs',
+            format: 'esm',
+            preserveModules: true,
+            generatedCode: {
+                preset: 'es2015',
+            }
+        }
+    ]
+})
diff --git a/packages/plugin-app-duration/app.js b/packages/plugin-app-duration/src/app-duration.ts
similarity index 51%
rename from packages/plugin-app-duration/app.js
rename to packages/plugin-app-duration/src/app-duration.ts
index 7d3c370bf3..7b96b7c9ba 100644
--- a/packages/plugin-app-duration/app.js
+++ b/packages/plugin-app-duration/src/app-duration.ts
@@ -1,15 +1,20 @@
+import { Plugin } from 'packages/core/types'
+
 let appStart = new Date()
 const reset = () => { appStart = new Date() }
 
-module.exports = {
+const plugin: Plugin = {
   name: 'appDuration',
   load: client => {
     client.addOnError(event => {
       const now = new Date()
 
-      event.app.duration = now - appStart
+      event.app.duration = Number(now) - Number(appStart)
+      // @ts-expect-error second argument is private API
     }, true)
 
     return { reset }
   }
 }
+
+export default plugin
diff --git a/packages/plugin-app-duration/test/app.test.ts b/packages/plugin-app-duration/test/app-duration.test.ts
similarity index 94%
rename from packages/plugin-app-duration/test/app.test.ts
rename to packages/plugin-app-duration/test/app-duration.test.ts
index 7f6911d16c..a8d234ad57 100644
--- a/packages/plugin-app-duration/test/app.test.ts
+++ b/packages/plugin-app-duration/test/app-duration.test.ts
@@ -1,4 +1,4 @@
-import plugin from '../app'
+import plugin from '../src/app-duration'
 import Client from '@bugsnag/core/client'
 import Event from '@bugsnag/core/event'
 
@@ -39,7 +39,7 @@ describe('plugin-app-duration', () => {
       }
     }
 
-    const result = plugin.load(client)
+    const result = plugin.load(client as unknown as Client)
 
     const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms))
 
diff --git a/packages/plugin-app-duration/tsconfig.json b/packages/plugin-app-duration/tsconfig.json
new file mode 100644
index 0000000000..c76cdab7cd
--- /dev/null
+++ b/packages/plugin-app-duration/tsconfig.json
@@ -0,0 +1,8 @@
+{
+    "extends": "../../tsconfig.json",
+    "include": ["src/**/*.ts"],
+    "compilerOptions": {
+      "target": "ES2020"
+    }
+}
+  
\ No newline at end of file
diff --git a/tsconfig.json b/tsconfig.json
index ba66910c52..2253bf436b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -66,7 +66,6 @@
     "packages/delivery-x-domain-request",
     "packages/delivery-xml-http-request",
     "packages/in-flight",
-    "packages/plugin-app-duration",
     "packages/plugin-aws-lambda",
     "packages/plugin-browser-context",
     "packages/plugin-browser-device",