diff --git a/.gitignore b/.gitignore
index 2d318e6..8602d1e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -62,5 +62,4 @@ typings/
 # dotenv environment variables file
 .env
 
-# next.js build output
-.next
+index.d.ts
diff --git a/index.d.ts b/index.d.ts
deleted file mode 100644
index 841e665..0000000
--- a/index.d.ts
+++ /dev/null
@@ -1,4 +0,0 @@
-/// <reference lib="dom"/>
-
-/* global Blob */
-export = Blob;
diff --git a/index.js b/index.js
index 5ad1e05..e163717 100644
--- a/index.js
+++ b/index.js
@@ -129,7 +129,7 @@ class Blob {
 	 *
 	 * @param {number} [start]
 	 * @param {number} [end]
-	 * @param {string} [contentType]
+	 * @param {string} [type]
 	 */
 	slice(start = 0, end = this.size, type = '') {
 		const {size} = this;
diff --git a/package.json b/package.json
index f303742..07d4b15 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,8 @@
     "lint": "xo",
     "test": "xo && ava",
     "report": "nyc ava",
-    "coverage": "nyc --reporter json --reporter text ava && codecov -f coverage/coverage-final.json"
+    "coverage": "nyc --reporter json --reporter text ava && codecov -f coverage/coverage-final.json",
+    "prepublishOnly": "tsc --declaration --emitDeclarationOnly --allowJs index.js"
   },
   "repository": "https://github.com/node-fetch/fetch-blob.git",
   "keywords": [
@@ -33,6 +34,7 @@
     "get-stream": "^5.1.0",
     "node-fetch": "^2.6.0",
     "nyc": "^15.0.1",
+    "typescript": "^3.9.5",
     "xo": "^0.32.0"
   },
   "xo": {