diff --git a/node/node.d.ts b/node/node.d.ts
index c2a8f71239..a9112d47a4 100644
--- a/node/node.d.ts
+++ b/node/node.d.ts
@@ -2596,7 +2596,7 @@ declare module "assert" {
             });
         }
 
-        export function fail(actual?: any, expected?: any, message?: string, operator?: string): void;
+        export function fail(actual: any, expected: any, message: string, operator: string): void;
         export function ok(value: any, message?: string): void;
         export function equal(actual: any, expected: any, message?: string): void;
         export function notEqual(actual: any, expected: any, message?: string): void;