diff --git a/types/node-polyglot/index.d.ts b/types/node-polyglot/index.d.ts
index 13d29d1193..e9cbbb831f 100644
--- a/types/node-polyglot/index.d.ts
+++ b/types/node-polyglot/index.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for node-polyglot v0.4.4
+// Type definitions for node-polyglot v2.4.0
 // Project: https://github.com/airbnb/polyglot.js
 // Definitions by: Tim Jackson-Kiely <https://github.com/timjk>
 //                 Liam Ross <https://github.com/liamross>
@@ -22,7 +22,7 @@ declare namespace Polyglot {
         phrases?: any;
         locale?: string;
         allowMissing?: boolean;
-        onMissingKey?: (key: string, options?: Polyglot.InterpolationOptions, locale?: string) => string;
+        onMissingKey?: (key: string, options: Polyglot.InterpolationOptions, locale: string) => string;
         warn?: (message: string) => void;
         interpolation?: InterpolationTokenOptions;
     }