diff --git a/src/classes/Agent.js b/src/classes/Agent.js
index 87a727d0..e7f55153 100644
--- a/src/classes/Agent.js
+++ b/src/classes/Agent.js
@@ -14,6 +14,8 @@ const log = Logger.child({
 });
 
 class Agent {
+  defaultPort: number;
+
   protocol: ProtocolType;
 
   fallbackAgent: AgentType;
@@ -22,8 +24,7 @@ class Agent {
 
   getUrlProxy: GetUrlProxyMethodType;
 
-  constructor (protocol: ProtocolType, mustUrlUseProxy: MustUrlUseProxyMethodType, getUrlProxy: GetUrlProxyMethodType, fallbackAgent: AgentType) {
-    this.protocol = protocol;
+  constructor (mustUrlUseProxy: MustUrlUseProxyMethodType, getUrlProxy: GetUrlProxyMethodType, fallbackAgent: AgentType) {
     this.fallbackAgent = fallbackAgent;
     this.mustUrlUseProxy = mustUrlUseProxy;
     this.getUrlProxy = getUrlProxy;
@@ -38,11 +39,13 @@ class Agent {
     });
 
     if (this.mustUrlUseProxy(requestUrl)) {
-      request.path = requestUrl;
+      if (this.protocol === 'http:') {
+        request.path = requestUrl;
+      }
 
       const proxy = this.getUrlProxy(requestUrl);
 
-      log.trace('proxying request to %s use %s proxy', requestUrl, 'http://' + proxy.hostname + ':' + proxy.port);
+      log.trace('proxying request to %s using %s proxy', requestUrl, 'http://' + proxy.hostname + ':' + proxy.port);
 
       request.shouldKeepAlive = false;
 
diff --git a/src/classes/HttpProxyAgent.js b/src/classes/HttpProxyAgent.js
index 3b052d95..7a9fea40 100644
--- a/src/classes/HttpProxyAgent.js
+++ b/src/classes/HttpProxyAgent.js
@@ -8,6 +8,15 @@ import type {
 import Agent from './Agent';
 
 class HttpProxyAgent extends Agent {
+  // @see https://github.com/sindresorhus/eslint-plugin-unicorn/issues/169#issuecomment-486980290
+  // eslint-disable-next-line unicorn/prevent-abbreviations
+  constructor (...args: *) {
+    super(...args);
+
+    this.protocol = 'http:';
+    this.defaultPort = 80;
+  }
+
   createConnection (configuration: ConnectionConfigurationType, callback: ConnectionCallbackType) {
     const socket = net.connect(
       configuration.proxy.port,
diff --git a/src/classes/HttpsProxyAgent.js b/src/classes/HttpsProxyAgent.js
index 0a38ae7f..7f172d24 100644
--- a/src/classes/HttpsProxyAgent.js
+++ b/src/classes/HttpsProxyAgent.js
@@ -9,6 +9,14 @@ import type {
 import Agent from './Agent';
 
 class HttpsProxyAgent extends Agent {
+  // eslint-disable-next-line unicorn/prevent-abbreviations
+  constructor (...args: *) {
+    super(...args);
+
+    this.protocol = 'https:';
+    this.defaultPort = 443;
+  }
+
   createConnection (configuration: ConnectionConfigurationType, callback: ConnectionCallbackType) {
     const socket = net.connect(
       configuration.proxy.port,
diff --git a/src/routines/bootstrap.js b/src/routines/bootstrap.js
index f9913bc0..060664ca 100644
--- a/src/routines/bootstrap.js
+++ b/src/routines/bootstrap.js
@@ -63,7 +63,6 @@ export default () => {
   // @see https://github.com/facebook/flow/issues/7670
   // $FlowFixMe
   http.globalAgent = new HttpProxyAgent(
-    'http:',
     mustUrlUseProxy,
     getUrlProxy,
     http.globalAgent
@@ -71,9 +70,8 @@ export default () => {
 
   // $FlowFixMe
   https.globalAgent = new HttpsProxyAgent(
-    'https:',
     mustUrlUseProxy,
     getUrlProxy,
-    http.globalAgent
+    https.globalAgent
   );
 };