diff --git a/package.json b/package.json
index a41ff13..5beb719 100644
--- a/package.json
+++ b/package.json
@@ -25,11 +25,13 @@
     "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
   ],
   "files": [
-    "index.js"
+    "index.js",
+    "types/index.d.ts"
   ],
-  "dependencies": {},
+  "types": "types/index.d.ts",
   "devDependencies": {
     "browserify": "^17.0.0",
+    "dtslint": "^4.0.0",
     "nyc": "^15.0.0",
     "prettier": "^2.0.0",
     "remark-cli": "^9.0.0",
@@ -45,7 +47,8 @@
     "build": "npm run build-bundle && npm run build-mangle",
     "test-api": "node test",
     "test-coverage": "nyc --reporter lcov tape test.js",
-    "test": "npm run format && npm run build && npm run test-coverage"
+    "test-types": "dtslint types",
+    "test": "npm run format && npm run build && npm run test-coverage && npm run test-types"
   },
   "prettier": {
     "tabWidth": 2,
@@ -59,7 +62,8 @@
     "prettier": true,
     "esnext": false,
     "ignore": [
-      "mdast-util-to-string.js"
+      "mdast-util-to-string.js",
+      "types/test.ts"
     ]
   },
   "nyc": {
diff --git a/types/index.d.ts b/types/index.d.ts
new file mode 100644
index 0000000..39b41db
--- /dev/null
+++ b/types/index.d.ts
@@ -0,0 +1,8 @@
+// Minimum TypeScript Version: 3.0
+import {Node} from 'unist'
+
+declare namespace mdastToString {}
+
+declare function mdastToString(node: Node | Node[]): string
+
+export = mdastToString
diff --git a/types/test.ts b/types/test.ts
new file mode 100644
index 0000000..2d7d7ad
--- /dev/null
+++ b/types/test.ts
@@ -0,0 +1,5 @@
+import * as mdastUtilToString from 'mdast-util-to-string'
+
+mdastUtilToString() // $ExpectError
+mdastUtilToString({type: 'root'}) // $ExpectType string
+mdastUtilToString([{type: 'root'}]) // $ExpectType string
diff --git a/types/tsconfig.json b/types/tsconfig.json
new file mode 100644
index 0000000..28f4cd1
--- /dev/null
+++ b/types/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "moduleResolution": "node",
+    "lib": [
+      "ES5"
+    ],
+    "strict": true,
+    "baseUrl": ".",
+    "paths": {
+      "mdast-util-to-string": [
+        "./index.d.ts"
+      ]
+    }
+  }
+}
diff --git a/types/tslint.json b/types/tslint.json
new file mode 100644
index 0000000..b818924
--- /dev/null
+++ b/types/tslint.json
@@ -0,0 +1,7 @@
+{
+"extends": "dtslint/dtslint.json",
+  "rules": {
+    "semicolon": false,
+    "whitespace": false
+  }
+}