diff --git a/types/nodemailer-mailgun-transport/index.d.ts b/types/nodemailer-mailgun-transport/index.d.ts
index 7945f1075f..63db09ae29 100644
--- a/types/nodemailer-mailgun-transport/index.d.ts
+++ b/types/nodemailer-mailgun-transport/index.d.ts
@@ -6,12 +6,15 @@
 import * as nodemailer from 'nodemailer';
 
 declare namespace mailgunTransport {
+    interface Options {
+        auth: AuthOptions;
+    }
     interface AuthOptions {
         api_key: string;
         domain?: string;
     }
 }
 
-declare function mailgunTransport(options: mailgunTransport.AuthOptions): nodemailer.Transport;
+declare function mailgunTransport(options: mailgunTransport.Options): nodemailer.Transport;
 
 export = mailgunTransport;
diff --git a/types/nodemailer-mailgun-transport/nodemailer-mailgun-transport-tests.ts b/types/nodemailer-mailgun-transport/nodemailer-mailgun-transport-tests.ts
index cdf2a9250c..20ab33766b 100644
--- a/types/nodemailer-mailgun-transport/nodemailer-mailgun-transport-tests.ts
+++ b/types/nodemailer-mailgun-transport/nodemailer-mailgun-transport-tests.ts
@@ -1,13 +1,17 @@
 import mailgunTransport = require('nodemailer-mailgun-transport');
 import nodemailer = require('nodemailer');
 
-const opts: mailgunTransport.AuthOptions = {
-	api_key: "harry"
+const opts: mailgunTransport.Options = {
+    auth: {
+        api_key: "harry"
+    }
 };
 
-const optsWithDomain: mailgunTransport.AuthOptions = {
-    api_key: "harry",
-    domain: "http://www.foo.com"
+const optsWithDomain: mailgunTransport.Options = {
+    auth: {
+        api_key: "harry",
+        domain: "http://www.foo.com"
+    }
 };
 
 const transport: nodemailer.Transporter = nodemailer.createTransport(mailgunTransport(optsWithDomain));