diff --git a/lib/LocalBinary.js b/lib/LocalBinary.js
index 8d694b2..a553559 100644
--- a/lib/LocalBinary.js
+++ b/lib/LocalBinary.js
@@ -218,10 +218,14 @@ function LocalBinary(){
 
       var options = url.parse(this.httpPath);
       if(conf.proxyHost && conf.proxyPort) {
-        options.agent = new HttpsProxyAgent({
+        var proxyOptions = {
           host: conf.proxyHost,
           port: conf.proxyPort
-        });
+        };
+        if(conf.proxyUser && conf.proxyPass) {
+          proxyOptions.auth = conf.proxyUser + ':' + conf.proxyPass;
+        }
+        options.agent = new HttpsProxyAgent(proxyOptions);
       }
       if (conf.useCaCertificate) {
         try {
diff --git a/test/local.js b/test/local.js
index 576ad79..e0886f7 100644
--- a/test/local.js
+++ b/test/local.js
@@ -482,6 +482,52 @@ describe('LocalBinary', function () {
       });
     });
 
+    it('should pass proxy authentication to the binary download when proxyUser/proxyPass are set', function () {
+      var https = require('https');
+      var getDownloadPathStub = sinon.stub(binary, 'getDownloadPath', function (conf, retries, cb) {
+        cb(null, 'https://bstack-downloads.example/BrowserStackLocal');
+      });
+      var httpsGetStub = sinon.stub(https, 'get').returns({ on: function () { return this; } });
+
+      try {
+        var conf = {
+          proxyHost: '127.0.0.1',
+          proxyPort: proxyPort,
+          proxyUser: 'user',
+          proxyPass: 'pass'
+        };
+        binary.download(conf, tempDownloadPath, function () {});
+
+        expect(httpsGetStub.calledOnce).to.equal(true);
+        var passedOptions = httpsGetStub.firstCall.args[0];
+        expect(passedOptions.agent).to.be.an('object');
+        expect(passedOptions.agent.proxy.auth).to.equal('user:pass');
+      } finally {
+        httpsGetStub.restore();
+        getDownloadPathStub.restore();
+      }
+    });
+
+    it('should not set proxy authentication when only host/port are provided', function () {
+      var https = require('https');
+      var getDownloadPathStub = sinon.stub(binary, 'getDownloadPath', function (conf, retries, cb) {
+        cb(null, 'https://bstack-downloads.example/BrowserStackLocal');
+      });
+      var httpsGetStub = sinon.stub(https, 'get').returns({ on: function () { return this; } });
+
+      try {
+        var conf = { proxyHost: '127.0.0.1', proxyPort: proxyPort };
+        binary.download(conf, tempDownloadPath, function () {});
+
+        var passedOptions = httpsGetStub.firstCall.args[0];
+        expect(passedOptions.agent).to.be.an('object');
+        expect(passedOptions.agent.proxy.auth).to.equal(undefined);
+      } finally {
+        httpsGetStub.restore();
+        getDownloadPathStub.restore();
+      }
+    });
+
     it('should download binaries in sync', function () {
       this.timeout(MAX_TIMEOUT);
       var conf = {};