diff --git a/lib/util.js b/lib/util.js
index 3147ef848..90db5d079 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -862,9 +862,10 @@ exports.validateEmptyString = function (value) {
 };
 
 exports.getProxyFromEnv = function (isHttps = true) {
-  const getDefaultPortIfNotSet = (proxyFromEnv, isHttps) => {
+  const getDefaultPortIfNotSet = (proxyFromEnv) => {
+    const isProxyProtocolHttps = proxyFromEnv.protocol === 'https:';
     if (!proxyFromEnv.port) {
-      return isHttps ? 443 : 80;
+      return isProxyProtocolHttps ? 443 : 80;
     } else {
       return proxyFromEnv.port;
     }
@@ -879,10 +880,9 @@ exports.getProxyFromEnv = function (isHttps = true) {
   if (proxyFromEnv.indexOf('://') === -1) {
     Logger.getInstance().info('Util.getProxyEnv: the protocol was missing from the environment proxy. Use the HTTP protocol.');
     proxyFromEnv = 'http' + '://' + proxyFromEnv;
-    isHttps = false;
   }
   proxyFromEnv = new URL(proxyFromEnv);
-  const port = getDefaultPortIfNotSet(proxyFromEnv, isHttps);
+  const port = getDefaultPortIfNotSet(proxyFromEnv);
   const proxy = {
     host: this.validateEmptyString(proxyFromEnv.hostname),
     port: Number(port),