diff --git a/lib/internal/url.js b/lib/internal/url.js
index cff94e6b7d2b5b..d9daef1524787d 100644
--- a/lib/internal/url.js
+++ b/lib/internal/url.js
@@ -400,7 +400,9 @@ Object.defineProperties(URL.prototype, {
           ret += '@';
         }
         ret += options.unicode ?
-          domainToUnicode(this.host) : this.host;
+          domainToUnicode(this.hostname) : this.hostname;
+        if (ctx.port !== null)
+          ret += `:${ctx.port}`;
       } else if (ctx.scheme === 'file:') {
         ret += '//';
       }
diff --git a/test/parallel/test-url-format-whatwg.js b/test/parallel/test-url-format-whatwg.js
index 26cef6063c212f..e5c3e369e80390 100644
--- a/test/parallel/test-url-format-whatwg.js
+++ b/test/parallel/test-url-format-whatwg.js
@@ -111,3 +111,8 @@ assert.strictEqual(
   url.format(myURL, { unicode: 0 }),
   'http://xn--lck1c3crb1723bpq4a.com/a?a=b#c'
 );
+
+assert.strictEqual(
+  url.format(new URL('http://xn--0zwm56d.com:8080/path'), { unicode: true }),
+  'http://测试.com:8080/path'
+);