diff --git a/src/api/api.ts b/src/api/api.ts
index eccfdcd..a80d507 100644
--- a/src/api/api.ts
+++ b/src/api/api.ts
@@ -5,14 +5,14 @@ import process = require('process');
 import _ = require('lodash');
 import { v4 as uuidv4 } from 'uuid';
 import * as url from 'url';
-import got from 'got';
+import got, { Agents } from 'got';
 import qs from 'qs';
 
 import { Environments, CLIENT_VERSION, API_VERSION } from '../constants';
 import * as GoCardlessErrors from '../errors';
 
-interface APIOptions {
-  proxy?: object;
+export interface APIOptions {
+  proxy?: Agents;
   raiseOnIdempotencyConflict?: boolean;
 }
 
@@ -36,7 +36,7 @@ export class Api {
   private _token: string;
   private _environment: Environments;
   private _baseUrl: string;
-  private _agent: object;
+  private _agent: Agents | undefined;
   private raiseOnIdempotencyConflict: boolean;
 
   private processVersion: string;
diff --git a/src/client.ts b/src/client.ts
index 45bc830..7783e8e 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1,7 +1,7 @@
 'use strict';
 
 import { Environments } from './constants';
-import { Api } from './api/api';
+import { Api, APIOptions } from './api/api';
 import { BankAuthorisationService } from './services/bankAuthorisationService';
 import { BankDetailsLookupService } from './services/bankDetailsLookupService';
 import { BillingRequestService } from './services/billingRequestService';
@@ -71,7 +71,7 @@ export class GoCardlessClient {
   private _verificationDetails: VerificationDetailService;
   private _webhooks: WebhookService;
 
-  constructor(token: string, environment = Environments.Live, options = {}) {
+  constructor(token: string, environment = Environments.Live, options: APIOptions = {}) {
     this._api = new Api(token, environment, options);
 
     this._bankAuthorisations = undefined;