diff --git a/package.json b/package.json
index 62977c5..314bfe1 100644
--- a/package.json
+++ b/package.json
@@ -23,14 +23,18 @@
   ],
   "files": [
     "lib",
-    "index.js"
+    "index.js",
+    "types/index.d.ts"
   ],
+  "types": "types",
   "dependencies": {
+    "@types/xast": "^1.0.0",
     "ccount": "^1.0.0",
     "stringify-entities": "^2.0.0"
   },
   "devDependencies": {
     "browserify": "^16.0.0",
+    "dtslint": "^4.0.0",
     "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^8.0.0",
@@ -45,7 +49,8 @@
     "format": "remark . -qfo && prettier . --write && xo --fix",
     "test-api": "node test",
     "test-coverage": "nyc --reporter lcov tape test/index.js",
-    "test": "npm run format && npm run test-coverage"
+    "test-types": "dtslint types",
+    "test": "npm run format && npm run test-coverage && npm run test-types"
   },
   "prettier": {
     "tabWidth": 2,
diff --git a/types/index.d.ts b/types/index.d.ts
new file mode 100644
index 0000000..4cb5b00
--- /dev/null
+++ b/types/index.d.ts
@@ -0,0 +1,56 @@
+// TypeScript Version: 3.0
+
+import {Node} from 'xast'
+
+declare namespace toXml {
+  interface Options {
+    /**
+     * Preferred quote to use.
+     *
+     * @default '"'
+     */
+    quote?: '"' | "'"
+
+    /**
+     * Use the other quote if that results in less bytes.
+     *
+     * @default false
+     */
+    quoteSmart?: boolean
+
+    /**
+     * Close elements without any content with slash (/) on the opening tag
+     * instead of an end tag: `<circle />` instead of `<circle></circle>`.
+     * See `tightClose` to control whether a space is used before the slash.
+     *
+     * @default false
+     */
+    closeEmptyElements?: boolean
+
+    /**
+     * Do not use an extra space when closing self-closing elements:
+     * `<circle/>` instead of `<circle />`.
+     *
+     * @default false
+     */
+    tightClose?: boolean
+
+    /**
+     * Allow `raw` nodes and insert them as raw XML. When falsey, encodes `raw` nodes.
+     * Only set this if you completely trust the content!
+     *
+     * @default false
+     */
+    allowDangerousXml?: boolean
+  }
+}
+
+/**
+ * Serialize the given xast tree to xml.
+ *
+ * @param tree Tree or list of nodes
+ * @param options Options
+ */
+declare function toXml(tree: Node | Node[], options?: toXml.Options): string
+
+export = toXml
diff --git a/types/test.ts b/types/test.ts
new file mode 100644
index 0000000..83c7d67
--- /dev/null
+++ b/types/test.ts
@@ -0,0 +1,22 @@
+import toXml = require('xast-util-to-xml')
+import {Element} from 'xast'
+
+const xmlns = 'http://www.sitemaps.org/schemas/sitemap/0.9'
+const element: Element = {
+  type: 'element',
+  name: 'urlset',
+  attributes: {xmlns},
+  children: []
+}
+
+toXml(element) // $ExpectType string
+toXml([element]) // $ExpectType string
+toXml(element, {allowDangerousXml: true}) // $ExpectType string
+toXml(element, {quote: "'"}) // $ExpectType string
+toXml(element, {quoteSmart: true}) // $ExpectType string
+toXml(element, {closeEmptyElements: true}) // $ExpectType string
+toXml(element, {closeEmptyElements: true, tightClose: true}) // $ExpectType string
+
+toXml() // $ExpectError
+toXml(false) // $ExpectError
+toXml(element, element) // $ExpectError
diff --git a/types/tsconfig.json b/types/tsconfig.json
new file mode 100644
index 0000000..5915e12
--- /dev/null
+++ b/types/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": ["es2015"],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "noEmit": true,
+    "baseUrl": ".",
+    "paths": {
+      "xast-util-to-xml": ["."]
+    }
+  }
+}
diff --git a/types/tslint.json b/types/tslint.json
new file mode 100644
index 0000000..4e872e2
--- /dev/null
+++ b/types/tslint.json
@@ -0,0 +1,9 @@
+{
+  "extends": "dtslint/dtslint.json",
+  "rules": {
+    "no-redundant-jsdoc": false,
+    "no-redundant-jsdoc-2": true,
+    "semicolon": false,
+    "whitespace": false
+  }
+}