diff --git a/types/mongodb/index.d.ts b/types/mongodb/index.d.ts
index 07b501f062..9709b724c3 100644
--- a/types/mongodb/index.d.ts
+++ b/types/mongodb/index.d.ts
@@ -15,7 +15,7 @@ import { ObjectID } from 'bson';
 import { EventEmitter } from 'events';
 import { Readable, Writable } from "stream";
 
-namespace MongoDB {
+declare namespace MongoDB {
     export function connect(uri: string, callback: MongoCallback<Db>): void;
     export function connect(uri: string, options?: MongoClientOptions): Promise<Db>;
     export function connect(uri: string, options: MongoClientOptions, callback: MongoCallback<Db>): void;