diff --git a/.editorconfig b/.editorconfig
index e98f58d..ea8f4ab 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -1,18 +1,17 @@
-# EditorConfig: http://EditorConfig.org
+# EditorConfig is awesome: https://EditorConfig.org
 
-# top-most EditorConfig file
 root = true
 
-# Unix-style newlines with a newline ending every file
 [*]
-charset = utf-8
 end_of_line = lf
-trim_trailing_whitespace = true
 insert_final_newline = true
+
+[*.{js,d.ts,ts}]
+charset = utf-8
+trim_trailing_whitespace = true
 indent_style = space
 indent_size = 4
 
-# 2 space indentation
-[*.yaml, *.yml]
+[package.json,*.yaml]
 indent_style = space
 indent_size = 2
diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..94f480d
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+* text=auto eol=lf
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index e7ef1ee..bac2cd5 100755
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 # Global
 node_modules/
+coverage
 
 # OS Generated
 .DS_Store*
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 16e1e6b..5d8a222 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/gender) (2022-01-11)
+* Added xo, tsd, c8.
+* Improved tests.
+
 <a name="2.0.1"></a>
 # [2.0.1](https://github.com/faker-javascript/gender) (2022-01-10)
 * GitHub docs updates.
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..1d98021
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,5 @@
+interface Options {
+    locale?: string;
+    extra?: string[];
+}
+export default function gender(options?: Options): string;
diff --git a/index.js b/index.js
index 05bf47b..af3a5da 100644
--- a/index.js
+++ b/index.js
@@ -1,17 +1,18 @@
+/* eslint camelcase: ["error", {properties: "never"}] */
 export default function gender(options) {
     options = options || {};
-    let genders = {
-        "en_US": [
-            "Male", 
-            "Female"
+    const genders = {
+        en_US: [
+            'Male',
+            'Female',
         ],
-        "ru_RU": [
-            "Мужской", 
-            "Женский"
+        ru_RU: [
+            'Мужской',
+            'Женский',
         ],
     };
-    let locale = options.locale || 'en_US';
-    let gendersWithExtra = genders[locale].concat(options.extra || []);
-    let randomGender = gendersWithExtra[Math.floor(Math.random() * gendersWithExtra.length)];
+    const locale = options.locale || 'en_US';
+    const gendersWithExtra = [...genders[locale], ...options.extra || []];
+    const randomGender = gendersWithExtra[Math.floor(Math.random() * gendersWithExtra.length)];
     return randomGender;
-};
\ No newline at end of file
+}
diff --git a/index.test-d.ts b/index.test-d.ts
new file mode 100644
index 0000000..600004f
--- /dev/null
+++ b/index.test-d.ts
@@ -0,0 +1,6 @@
+import {expectType} from 'tsd';
+import gender from './index.js';
+
+expectType<string>(gender());
+expectType<string>(gender({locale: 'en_US'}));
+expectType<string>(gender({locale: 'en_US', extra: ['gender']}));
diff --git a/package.json b/package.json
index 66dfd1e..043b8c6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@fakerjs/gender",
-  "version": "2.0.1",
+  "version": "2.1.0",
   "description": "Gender package provides functionality to generate a fake gender value.",
   "license": "MIT",
   "repository": "faker-javascript/gender",
@@ -15,13 +15,17 @@
     "node": ">=12"
   },
   "scripts": {
-    "test": "ava"
+    "test": "c8 ava; xo --space 4; tsd;"
   },
   "devDependencies": {
-    "ava": "^3.15.0"
+    "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",