diff --git a/os-locale/os-locale-tests.ts b/os-locale/os-locale-tests.ts
new file mode 100644
index 000000000..65763a112
--- /dev/null
+++ b/os-locale/os-locale-tests.ts
@@ -0,0 +1,8 @@
+/// <reference path="./os-locale.d.ts" />
+
+import osLocale, { sync } from 'os-locale';
+
+osLocale((err: any, locale: string) => {
+});
+
+var locale: string = sync();
diff --git a/os-locale/os-locale.d.ts b/os-locale/os-locale.d.ts
new file mode 100644
index 000000000..17933ae67
--- /dev/null
+++ b/os-locale/os-locale.d.ts
@@ -0,0 +1,12 @@
+// Type definitions for os-locale 1.2.1
+// Project: https://github.com/sindresorhus/os-locale
+// Definitions by: Aya Morisawa <https://github.com/AyaMorisawa>
+// Definitions: https://github.com/borisyankov/DefinitelyTyped
+
+declare module "os-locale" {
+	function osLocale(cb: (err: any, locale: string) => void): void;
+	function osLocaleSync(): string;
+	
+	export { osLocaleSync as sync };
+	export default osLocale;
+}