diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..00c9fe2
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,55 @@
+// Project: Immutability helper
+// TypeScript Version: 2.2
+
+export = update
+
+// declare function update<T>(data: T, query: update.Query<T>): T
+declare function update<T>(
+  data: ReadonlyArray<T>,
+  query: ArrayOperators<T>,
+): ReadonlyArray<T>
+
+declare function update<T>(
+  data: ReadonlySet<T>,
+  query: SetOperators<T>,
+): ReadonlySet<T>
+
+declare function update<K, V>(
+  data: ReadonlyMap<K, V>,
+  query: MapOperators<K, V>,
+): ReadonlyMap<K, V>
+
+declare function update<T>(data: T, query: Query<T>): object
+
+type Tree<T> = {[K in keyof T]?: Query<T[K]>}
+type Query<T> =
+  | Tree<T>
+  | ObjectOperators<T>
+  | ArrayOperators<any>
+  | SetOperators<any>
+
+type ObjectOperators<T> =
+  | {$set: any}
+  | {$toggle: Array<keyof T>}
+  | {$unset: Array<keyof T>}
+  | {$merge: Partial<T>}
+  | {$apply: (old: T) => T}
+  | ((old: T) => any)
+type ArrayOperators<T> =
+  | {$push: T}
+  | {$unshift: T}
+  | {$splice: Array<[number, number]>}
+
+type MapOperators<K, V> = {$add: Array<[K, V]>} | {$remove: K[]}
+type SetOperators<T> = {$add: T[]} | {$remove: T[]}
+
+declare namespace update {
+  function newContext(): typeof update
+  function extend<T>(
+    command: Command,
+    handler: (param: CommandArg, old: T) => T,
+  ): void
+
+  type Command = string
+  type CommandArg = any
+}
diff --git a/package.json b/package.json
index 9829391..145f182 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,8 @@
   "scripts": {
     "test-cov": "nyc npm test && nyc report --reporter=lcov",
     "test-travis": "nyc npm test && nyc report --reporter=lcov",
-    "test": "mocha test.js"
+    "test": "mocha test.js",
+    "test-dtslint": "dtslint"
   },
   "keywords": [
     "immutability"
@@ -16,6 +17,7 @@
   "license": "MIT",
   "devDependencies": {
     "coveralls": "^2.11.6",
+    "dtslint": "^0.2.0",
     "expect": "^1.14.0",
     "mocha": "^2.4.5",
     "nyc": "^5.6.0"
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..0d76f1b
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": ["es6"],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "noEmit": true,
+    "strictFunctionTypes": false,
+
+    "baseUrl": ".",
+    "paths": { "immutability-helper": ["."] }
+  }
+}
+
diff --git a/tslint.json b/tslint.json
new file mode 100644
index 0000000..e1e3a54
--- /dev/null
+++ b/tslint.json
@@ -0,0 +1,7 @@
+{
+    "extends": "dtslint/dtslint.json",
+    "rules": {
+        "semicolon": false
+    }
+}
+