diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..da62dcc
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,12 @@
+
+export function MovingAverage (timespan:number): MovingAverage
+export interface MovingAverage {
+  variance: () => number
+  movingAverage: () => number
+
+  deviation: () => number
+  forecast: () => number
+
+  push: (time: number, value: number) => void
+}
+export = MovingAverage
diff --git a/package.json b/package.json
index 92352aa..7c820fb 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "1.0.0",
   "description": "Exponential Moving Average",
   "main": "index.js",
+  "types": "index.d.ts",
   "scripts": {
     "test": "npm run lint && npm run test:node",
     "test:node": "node tests/moving_average.js",