diff --git a/os-locale/os-locale-tests.ts b/os-locale/os-locale-tests.ts
index 65763a112..bcf5b0129 100644
--- a/os-locale/os-locale-tests.ts
+++ b/os-locale/os-locale-tests.ts
@@ -5,4 +5,8 @@ import osLocale, { sync } from 'os-locale';
 osLocale((err: any, locale: string) => {
 });
 
-var locale: string = sync();
+osLocale({spawn: false}, (err: any, locale: string) => {
+});
+
+var locale1: string = sync();
+var locale2: string = sync({spawn: false});
diff --git a/os-locale/os-locale.d.ts b/os-locale/os-locale.d.ts
index 17933ae67..74b2d6922 100644
--- a/os-locale/os-locale.d.ts
+++ b/os-locale/os-locale.d.ts
@@ -1,12 +1,14 @@
-// Type definitions for os-locale 1.2.1
+// Type definitions for os-locale 1.4.0
 // 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(options: {spawn?: boolean}, cb: (err: any, locale: string) => void): void;
 	function osLocale(cb: (err: any, locale: string) => void): void;
 	function osLocaleSync(): string;
-	
+	function osLocaleSync(options: {spawn?: boolean}): string;
+
 	export { osLocaleSync as sync };
 	export default osLocale;
 }