diff --git a/lib/tunnel.js b/lib/tunnel.js
index 10cc382..8175648 100644
--- a/lib/tunnel.js
+++ b/lib/tunnel.js
@@ -119,7 +119,7 @@ TunnelingAgent.prototype.createSocket = function createSocket(options, cb) {
   if (connectOptions.proxyAuth) {
     connectOptions.headers = connectOptions.headers || {};
     connectOptions.headers['Proxy-Authorization'] = 'Basic ' +
-        new Buffer(connectOptions.proxyAuth).toString('base64');
+        Buffer.from(connectOptions.proxyAuth).toString('base64');
   }
 
   debug('making CONNECT request');