diff --git a/types/task-worklet/index.d.ts b/types/task-worklet/index.d.ts
index e1c68ffd84..69e52bf4ef 100644
--- a/types/task-worklet/index.d.ts
+++ b/types/task-worklet/index.d.ts
@@ -2,11 +2,11 @@
 // Project: https://github.com/GoogleChromeLabs/task-worklet
 // Definitions by: Karol Majewski <https://github.com/karol-majewski>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
-// TypeScript Version: 3.1
+// TypeScript Version: 2.9
 
-declare class TaskQueue<T extends TaskDescriptor = any> {
+declare class TaskQueue {
     constructor(options?: Options);
-    postTask<U extends T = any>(taskName: U['name'], ...args: Parameters<U>): Task<ReturnType<U>>;
+    postTask(taskName: string, ...args: any[]): Task;
     addModule(moduleURL: string): Promise<void>;
 }
 
@@ -14,12 +14,7 @@ interface Options {
     size?: number;
 }
 
-interface TaskDescriptor {
-    name: string;
-    (...args: any): any;
-}
-
-export interface Task<T = unknown> {
+export interface Task<T = any> {
     id: number;
     state: State;
     result: Promise<T>;
diff --git a/types/task-worklet/package.json b/types/task-worklet/package.json
new file mode 100644
index 0000000000..49b3fec869
--- /dev/null
+++ b/types/task-worklet/package.json
@@ -0,0 +1,14 @@
+{
+    "private": true,
+    "types": "index",
+    "typesVersions": {
+        ">=3.1.0-0": {
+            "*": [
+                "ts3.1/*"
+            ]
+        }
+    },
+    "dependencies": {
+        "typescript": ">2.9.0"
+    }
+}
diff --git a/types/task-worklet/task-worklet-tests.ts b/types/task-worklet/task-worklet-tests.ts
index 30a5072a2b..c4abfe898b 100644
--- a/types/task-worklet/task-worklet-tests.ts
+++ b/types/task-worklet/task-worklet-tests.ts
@@ -5,16 +5,16 @@ interface Fetcher {
   (input: RequestInfo, init?: RequestInit): Promise<Response>;
 }
 
-const unsafe = new TaskQueue();                                       // $ExpectType TaskQueue<any>
-const withEmptyOptions = new TaskQueue({});                           // $ExpectType TaskQueue<any>
-const withValidOptions = new TaskQueue({ size: 2 });                  // $ExpectType TaskQueue<any>
+const unsafe = new TaskQueue();                                       // $ExpectType TaskQueue
+const withEmptyOptions = new TaskQueue({});                           // $ExpectType TaskQueue
+const withValidOptions = new TaskQueue({ size: 2 });                  // $ExpectType TaskQueue
 
-const queue = new TaskQueue<Fetcher>();                               // $ExpectType TaskQueue<Fetcher>
+const queue = new TaskQueue();                                        // $ExpectType TaskQueue
 queue.addModule('/fetcher-worklet.js');                               // $ExpectType Promise<void>
-const task = queue.postTask<Fetcher>('fetch', 'https://example.com'); // $ExpectType Task<Promise<Response>>
+const task = queue.postTask('fetch', 'https://example.com');          // $ExpectType Task
 
 async () => {
-  const result = await task.result;                                   // $ExpectType Response
+  const result = await task.result;                                   // $ExpectType any
   const id = task.id;                                                 // $ExpectType number
   const state = task.state;                                           // $ExpectType State
 };
diff --git a/types/task-worklet/ts3.1/index.d.ts b/types/task-worklet/ts3.1/index.d.ts
new file mode 100644
index 0000000000..158b9b40af
--- /dev/null
+++ b/types/task-worklet/ts3.1/index.d.ts
@@ -0,0 +1,30 @@
+declare class TaskQueue<T extends TaskDescriptor = any> {
+    constructor(options?: Options);
+    postTask<U extends T = any>(taskName: U['name'], ...args: Parameters<U>): Task<ReturnType<U>>;
+    addModule(moduleURL: string): Promise<void>;
+}
+
+interface Options {
+    size?: number;
+}
+
+interface TaskDescriptor {
+    name: string;
+    (...args: any): any;
+}
+
+export interface Task<T = unknown> {
+    id: number;
+    state: State;
+    result: Promise<T>;
+}
+
+export type State =
+    | 'cancelled'
+    | 'completed'
+    | 'fulfilled'
+    | 'pending'
+    | 'scheduled';
+
+export default TaskQueue;
+export as namespace TaskQueue;
diff --git a/types/task-worklet/ts3.1/task-worklet-tests.ts b/types/task-worklet/ts3.1/task-worklet-tests.ts
new file mode 100644
index 0000000000..30a5072a2b
--- /dev/null
+++ b/types/task-worklet/ts3.1/task-worklet-tests.ts
@@ -0,0 +1,23 @@
+import TaskQueue, { Task, State } from 'task-worklet';
+
+interface Fetcher {
+  name: 'fetch';
+  (input: RequestInfo, init?: RequestInit): Promise<Response>;
+}
+
+const unsafe = new TaskQueue();                                       // $ExpectType TaskQueue<any>
+const withEmptyOptions = new TaskQueue({});                           // $ExpectType TaskQueue<any>
+const withValidOptions = new TaskQueue({ size: 2 });                  // $ExpectType TaskQueue<any>
+
+const queue = new TaskQueue<Fetcher>();                               // $ExpectType TaskQueue<Fetcher>
+queue.addModule('/fetcher-worklet.js');                               // $ExpectType Promise<void>
+const task = queue.postTask<Fetcher>('fetch', 'https://example.com'); // $ExpectType Task<Promise<Response>>
+
+async () => {
+  const result = await task.result;                                   // $ExpectType Response
+  const id = task.id;                                                 // $ExpectType number
+  const state = task.state;                                           // $ExpectType State
+};
+
+new TaskQueue({ size: 1, excessProperty: true });                     // $ExpectError
+queue.postTask<Fetcher>('incorrect-task-name');                       // $ExpectError
diff --git a/types/task-worklet/ts3.1/tsconfig.json b/types/task-worklet/ts3.1/tsconfig.json
new file mode 100644
index 0000000000..e5076ca083
--- /dev/null
+++ b/types/task-worklet/ts3.1/tsconfig.json
@@ -0,0 +1,24 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6",
+            "dom"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "baseUrl": "../../",
+        "typeRoots": [
+            "../../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true,
+        "strictFunctionTypes": true
+    },
+    "files": [
+        "index.d.ts",
+        "task-worklet-tests.ts"
+    ]
+}
diff --git a/types/task-worklet/ts3.1/tslint.json b/types/task-worklet/ts3.1/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/task-worklet/ts3.1/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }