diff --git a/request.js b/request.js
index 9d3fc3e92..90bed4f4a 100644
--- a/request.js
+++ b/request.js
@@ -287,10 +287,14 @@ Request.prototype.init = function (options) {
   self.setHost = false
   if (!self.hasHeader('host')) {
     var hostHeaderName = self.originalHostHeaderName || 'host'
-    // When used with an IPv6 address, `host` will provide
-    // the correct bracketed format, unlike using `hostname` and
-    // optionally adding the `port` when necessary.
     self.setHeader(hostHeaderName, self.uri.host)
+    // Drop :port suffix from Host header if known protocol.
+    if (self.uri.port) {
+      if ((self.uri.port === '80' && self.uri.protocol === 'http:') ||
+          (self.uri.port === '443' && self.uri.protocol === 'https:')) {
+        self.setHeader(hostHeaderName, self.uri.hostname)
+      }
+    }
     self.setHost = true
   }
 
diff --git a/tests/test-headers.js b/tests/test-headers.js
index b80c9b312..59faae87e 100644
--- a/tests/test-headers.js
+++ b/tests/test-headers.js
@@ -180,6 +180,56 @@ tape('undefined headers', function (t) {
   })
 })
 
+tape('preserve port in host header if non-standard port', function (t) {
+  var r = request({
+    url: s.url + '/headers.json'
+  }, function (err, res, body) {
+    t.equal(err, null)
+    t.equal(r.originalHost, 'localhost:' + s.port)
+    t.end()
+  })
+})
+
+tape('strip port in host header if explicit standard port (:80) & protocol (HTTP)', function (t) {
+  var r = request({
+    url: 'http://localhost:80/headers.json'
+  }, function (err, res, body) {
+    t.notEqual(err, null)
+    t.equal(r.req.socket._host, 'localhost')
+    t.end()
+  })
+})
+
+tape('strip port in host header if explicit standard port (:443) & protocol (HTTPS)', function (t) {
+  var r = request({
+    url: 'https://localhost:443/headers.json'
+  }, function (err, res, body) {
+    t.notEqual(err, null)
+    t.equal(r.req.socket._host, 'localhost')
+    t.end()
+  })
+})
+
+tape('strip port in host header if implicit standard port & protocol (HTTP)', function (t) {
+  var r = request({
+    url: 'http://localhost/headers.json'
+  }, function (err, res, body) {
+    t.notEqual(err, null)
+    t.equal(r.req.socket._host, 'localhost')
+    t.end()
+  })
+})
+
+tape('strip port in host header if implicit standard port & protocol (HTTPS)', function (t) {
+  var r = request({
+    url: 'https://localhost/headers.json'
+  }, function (err, res, body) {
+    t.notEqual(err, null)
+    t.equal(r.req.socket._host, 'localhost')
+    t.end()
+  })
+})
+
 var isExpectedHeaderCharacterError = function (headerName, err) {
   return err.message === 'The header content contains invalid characters' ||
     err.message === ('Invalid character in header content ["' + headerName + '"]')