diff --git a/lib/Connection.js b/lib/Connection.js
index e90182453..9560b40cf 100644
--- a/lib/Connection.js
+++ b/lib/Connection.js
@@ -191,7 +191,8 @@ class Connection {
       path: '',
       href: url.href,
       origin: url.origin,
-      port: url.port,
+      // https://github.com/elastic/elasticsearch-js/issues/843
+      port: url.port !== '' ? url.port : undefined,
       headers: this.headers,
       auth: !!url.username === true || !!url.password === true
         ? `${url.username}:${url.password}`
diff --git a/test/unit/connection.test.js b/test/unit/connection.test.js
index 84068cad5..4d1040280 100644
--- a/test/unit/connection.test.js
+++ b/test/unit/connection.test.js
@@ -763,3 +763,34 @@ test('Util.inspect Connection class should hide agent and ssl', t => {
   roles: { master: true, data: true, ingest: true, ml: false } }`)
   )
 })
+
+// https://github.com/elastic/elasticsearch-js/issues/843
+test('Port handling', t => {
+  t.test('http 80', t => {
+    const connection = new Connection({
+      url: new URL('http://localhost:80')
+    })
+
+    t.strictEqual(
+      connection.buildRequestObject({}).port,
+      undefined
+    )
+
+    t.end()
+  })
+
+  t.test('https 443', t => {
+    const connection = new Connection({
+      url: new URL('https://localhost:443')
+    })
+
+    t.strictEqual(
+      connection.buildRequestObject({}).port,
+      undefined
+    )
+
+    t.end()
+  })
+
+  t.end()
+})