diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 70ae2d3..2026a0d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [6.x, 8.x, 10.x, 11.x, 12.x, 13.x, 14.x, 15.x]
+        node-version: [10.x, 11.x, 12.x, 13.x, 14.x, 15.x]
     steps:
     - uses: actions/checkout@v2
     - name: Use Node.js ${{ matrix.node-version }}
@@ -25,3 +25,18 @@ jobs:
       run: npm install --ignore-scripts
     - name: Test
       run: npm run test
+  test-legacy:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [6.x, 8.x]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v2.1.5
+      with:
+        node-version: ${{ matrix.node-version }}
+    - name: Install Dependencies
+      run: npm install --ignore-scripts
+    - name: Test
+      run: npm run test-legacy
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..0c15f9e
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,60 @@
+export type ParseOptions = {
+  /**
+   * What to do when a `__proto__` key is found.
+    * - `'error'` - throw a `SyntaxError` when a `__proto__` key is found. This is the default value.
+    * - `'remove'` - deletes any `__proto__` keys from the result object.
+    * - `'ignore'` - skips all validation (same as calling `JSON.parse()` directly).
+    */
+  protoAction?: 'error' | 'remove' | 'ignore',
+  /**
+   * What to do when a `constructor` key is found.
+   * - `'error'` - throw a `SyntaxError` when a `constructor.prototype` key is found. This is the default value.
+   * - `'remove'` - deletes any `constructor` keys from the result object.
+   * - `'ignore'` - skips all validation (same as calling `JSON.parse()` directly).
+   */
+  constructorAction?: 'error' | 'remove' | 'ignore',
+}
+
+export type ScanOptions = {
+  /**
+   * What to do when a `__proto__` key is found.
+    * - `'error'` - throw a `SyntaxError` when a `__proto__` key is found. This is the default value.
+    * - `'remove'` - deletes any `__proto__` keys from the input `obj`.
+    */
+  protoAction?: 'error' | 'remove',
+  /**
+   * What to do when a `constructor` key is found.
+   * - `'error'` - throw a `SyntaxError` when a `constructor.prototype` key is found. This is the default value.
+   * - `'remove'` - deletes any `constructor` keys from the input `obj`.
+   */
+  constructorAction?: 'error' | 'remove',
+}
+
+type Reviver = (this: any, key: string, value: any) => any
+
+/**
+ * Parses a given JSON-formatted text into an object.
+ *
+ * @param text The JSON text string.
+ * @param reviver The `JSON.parse()` optional `reviver` argument.
+ * @param options Optional configuration object.
+ * @returns The parsed object.
+ */
+export function parse(text: string | Buffer, reviver?: Reviver | null, options?: ParseOptions): any
+
+/**
+ * Parses a given JSON-formatted text into an object.
+ *
+ * @param text The JSON text string.
+ * @param reviver The `JSON.parse()` optional `reviver` argument.
+ * @returns The parsed object, or `null` if there was an error or if the JSON contained possibly insecure properties.
+ */
+export function safeParse(text: string | Buffer, reviver?: Reviver | null): any
+
+/**
+ * Scans a given object for prototype properties.
+ *
+ * @param obj The object being scanned.
+ * @param options Optional configuration object.
+ */
+export function scan(obj: any, options?: ScanOptions): void
diff --git a/index.test-d.ts b/index.test-d.ts
new file mode 100644
index 0000000..002f2f9
--- /dev/null
+++ b/index.test-d.ts
@@ -0,0 +1,30 @@
+import { expectType, expectError } from 'tsd'
+import sjson = require('.')
+
+expectError(sjson.parse(null))
+expectType<any>(sjson.parse('{"anything":0}'))
+
+sjson.parse('"test"', null, { protoAction: 'remove' })
+expectError(sjson.parse('"test"', null, { protoAction: 'incorrect' }))
+sjson.parse('"test"', null, { constructorAction: 'ignore' })
+expectError(sjson.parse('"test"', null, { constructorAction: 'incorrect' }))
+
+sjson.safeParse('"test"', null)
+sjson.safeParse('"test"')
+expectError(sjson.safeParse(null))
+
+sjson.scan('"test"', { protoAction: 'remove' })
+expectError(sjson.scan('"test"', { protoAction: 'ignore' }))
+sjson.scan('"test"', { constructorAction: 'error' })
+expectError(sjson.scan('"test"', { constructorAction: 'ignore' }))
+
+declare const input: Buffer
+sjson.parse(input)
+sjson.safeParse(input)
+
+sjson.parse('{"anything":0}', (key, value) => {
+  expectType<string>(key)
+})
+sjson.safeParse('{"anything":0}', (key, value) => {
+  expectType<string>(key)
+})
diff --git a/package.json b/package.json
index d284b1a..4536142 100644
--- a/package.json
+++ b/package.json
@@ -3,9 +3,11 @@
   "version": "2.3.2",
   "description": "JSON parse with prototype poisoning protection",
   "main": "index.js",
+  "types": "index.d.ts",
   "scripts": {
     "benchmark": "cd benchmarks && npm install && npm run all",
-    "test": "standard && nyc tape test.js",
+    "test-legacy": "nyc tape test.js",
+    "test": "standard && tsd && nyc tape test.js",
     "test-in-browsers": "airtap test.js"
   },
   "repository": {
@@ -31,6 +33,7 @@
     "nyc": "^14.1.1",
     "playwright": "^1.7.1",
     "standard": "^16.0.0",
-    "tape": "^5.1.1"
+    "tape": "^5.1.1",
+    "tsd": "^0.14.0"
   }
 }