diff --git a/lib/pooler.js b/lib/pooler.js
index 0bb5c8b..de08e94 100644
--- a/lib/pooler.js
+++ b/lib/pooler.js
@@ -1,10 +1,7 @@
 const util = require('util');
 const EventEmitter = require('events').EventEmitter;
-const AWS = require('aws-sdk');
 const Task = require('./task.js');
 
-const stepfunction = new AWS.StepFunctions();
-
 /**
 * @class Pooler
 * @param {object} options
@@ -82,7 +79,7 @@ Pooler.prototype.pool = function () {
 
 Pooler.prototype.getActivityTask = function () {
 	this.logger.debug(this.workerName + ' getActivityTask ' + this.activityArn);
-	this._request = stepfunction.getActivityTask({
+	this._request = this.worker.stepfunction.getActivityTask({
 		activityArn: this.activityArn,
 		workerName: this.workerName
 	}, (err, data) => {
diff --git a/lib/worker.js b/lib/worker.js
index 25bc919..5229ab6 100644
--- a/lib/worker.js
+++ b/lib/worker.js
@@ -2,7 +2,6 @@ const EventEmitter = require('events').EventEmitter;
 const util = require('util');
 const AWS = require('aws-sdk');
 
-const stepfunction = new AWS.StepFunctions();
 const Pooler = require('./pooler.js');
 const replaceError = require('./replace-error.js');
 
@@ -15,10 +14,16 @@ const replaceError = require('./replace-error.js');
 * @param {boolean} [options.autoStart=true]
 * @param {boolean} [options.logger=null] winston-like logger
 * @param {string} [options.concurrency=1]
+* @param {AWSConfig} [options.awsConfig={}]
 * */
 
+/**
+* @typedef {Object} AWSConfig see https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/Config.html
+*/
 function Worker(options) {
 	EventEmitter.call(this);
+	const awsConfig = options.awsConfig || {};
+	this.stepfunction = new AWS.StepFunctions(awsConfig);
 
 	this.autoStart = typeof (options.autoStart) === 'boolean' ? options.autoStart : true;
 
@@ -126,7 +131,7 @@ Worker.prototype.execute = function (input, cb, heartbeat) {
 Worker.prototype.succeed = function (res) {
 	const params = Object.assign({}, res, {output: JSON.stringify(res.output)});
 	delete params.workerName;
-	stepfunction.sendTaskSuccess(params, err => {
+	this.stepfunction.sendTaskSuccess(params, err => {
 		if (err) {
 			this.emit('error', err);
 		} else {
@@ -146,7 +151,7 @@ Worker.prototype.fail = function (res) {
 	const params = Object.assign({}, res, {error});
 	delete params.workerName;
 	this.logger.debug('sendTaskFailure', res.error);
-	stepfunction.sendTaskFailure(params, err => {
+	this.stepfunction.sendTaskFailure(params, err => {
 		if (err) {
 			this.emit('error', err);
 		} else {
@@ -160,7 +165,7 @@ Worker.prototype.heartbeat = function (res) {
 	delete params.workerName;
 	this.logger.debug('sendTaskHeartbeat');
 
-	stepfunction.sendTaskHeartbeat(params, err => {
+	this.stepfunction.sendTaskHeartbeat(params, err => {
 		if (err) {
 			this.emit('error', err);
 		} else {