diff --git a/CHANGELOG.md b/CHANGELOG.md
index 075f33d..34c0cde 100755
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+<a name="2.1.0"></a>
+# [2.1.0](https://github.com/faker-javascript/age) (2022-01-11)
+* Added xo, tsd, c8.
+* Improved tests.
+
 <a name="2.0.0"></a>
 # [2.0.0](https://github.com/faker-javascript/age) (2022-01-09)
 
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..057fbb1
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,4 @@
+interface Options {
+    type: string;
+}
+export default function age(options?: Options): number;
diff --git a/index.js b/index.js
index bccf470..ea25133 100644
--- a/index.js
+++ b/index.js
@@ -4,31 +4,32 @@ export default function age(options) {
     let max = 100;
     switch (options.type) {
         case 'child':
-            min = 0; 
+            min = 0;
             max = 12;
             break;
         case 'teen':
-            min = 13; 
+            min = 13;
             max = 19;
             break;
         case 'adult':
-            min = 18; 
+            min = 18;
             max = 65;
             break;
         case 'senior':
-            min = 65; 
+            min = 65;
             max = 100;
             break;
         case 'all':
-            min = 0; 
+            min = 0;
             max = 100;
             break;
         default:
-            min = 0; 
+            min = 0;
             max = 100;
             break;
     }
+
     min = Math.ceil(min);
     max = Math.floor(max);
     return Math.floor(Math.random() * (max - min + 1)) + min;
-};
\ No newline at end of file
+}
diff --git a/index.test-d.ts b/index.test-d.ts
new file mode 100644
index 0000000..3782e36
--- /dev/null
+++ b/index.test-d.ts
@@ -0,0 +1,9 @@
+import {expectType} from 'tsd';
+import age from './index.js';
+
+expectType<number>(age());
+expectType<number>(age({type: 'child'}));
+expectType<number>(age({type: 'teen'}));
+expectType<number>(age({type: 'adult'}));
+expectType<number>(age({type: 'senior'}));
+expectType<number>(age({type: 'all'}));
diff --git a/package.json b/package.json
index 143d7d9..6155d03 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@fakerjs/age",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "Age package provides functionality to generate a fake age value.",
   "license": "MIT",
   "repository": "faker-javascript/age",
@@ -15,14 +15,17 @@
     "node": ">=12"
   },
   "scripts": {
-    "test": "c8 ava"
+    "test": "c8 ava; xo --space 4; tsd;"
   },
   "devDependencies": {
-    "ava": "^3.15.0",
-    "c8": "^7.11.0"
+    "ava": "^4.0.0",
+    "c8": "^7.11.0",
+		"tsd": "^0.19.1",
+		"xo": "^0.47.0"
   },
   "files": [
-    "index.js"
+    "index.js",
+    "index.d.ts"
   ],
   "keywords": [
     "fakerjs",
diff --git a/test.js b/test.js
index 66890e1..a9e6968 100644
--- a/test.js
+++ b/test.js
@@ -1,31 +1,31 @@
-import age from './index.js';
 import test from 'ava';
+import age from './index.js';
 
 test('age return type to be number', t => {
-	t.is(typeof age(), 'number');
+    t.is(typeof age(), 'number');
 });
 
 test('age with type child less than 13 and more than -1', t => {
-	t.true(age({type: 'child'}) < 13);
-	t.true(age({type: 'child'}) > -1);
+    t.true(age({type: 'child'}) < 13);
+    t.true(age({type: 'child'}) > -1);
 });
 
 test('age with type teen less than 20 and more than 12', t => {
-	t.true(age({type: 'teen'}) < 20);
-	t.true(age({type: 'teen'}) > 12);
+    t.true(age({type: 'teen'}) < 20);
+    t.true(age({type: 'teen'}) > 12);
 });
 
 test('age with type adult less than 69 and more than 17', t => {
-	t.true(age({type: 'adult'}) < 69);
-	t.true(age({type: 'adult'}) > 17);
+    t.true(age({type: 'adult'}) < 69);
+    t.true(age({type: 'adult'}) > 17);
 });
 
 test('age with type senior less than 101 and more than 64', t => {
-	t.true(age({type: 'senior'}) < 101);
-	t.true(age({type: 'senior'}) > 64);
+    t.true(age({type: 'senior'}) < 101);
+    t.true(age({type: 'senior'}) > 64);
 });
 
 test('age with type all less than 101 and more than -1', t => {
-	t.true(age({type: 'all'}) < 101);
-	t.true(age({type: 'all'}) > -1);
-});
\ No newline at end of file
+    t.true(age({type: 'all'}) < 101);
+    t.true(age({type: 'all'}) > -1);
+});