diff --git a/lib/internal/url.js b/lib/internal/url.js
index 07d2e2241ddfe4..ed25b2d2188fa1 100644
--- a/lib/internal/url.js
+++ b/lib/internal/url.js
@@ -571,11 +571,13 @@ ObjectDefineProperties(URLSearchParams.prototype, {
  * We use `href` and `protocol` as they are the only properties that are
  * easy to retrieve and calculate due to the lazy nature of the getters.
  *
+ * We check for auth attribute to distinguish legacy url instance with
+ * WHATWG URL instance.
  * @param {*} self
  * @returns {self is URL}
  */
 function isURL(self) {
-  return Boolean(self?.href && self.protocol);
+  return Boolean(self?.href && self.protocol && self.auth === undefined);
 }
 
 class URL {
diff --git a/test/parallel/test-url-is-url.js b/test/parallel/test-url-is-url.js
new file mode 100644
index 00000000000000..0b42bb3b2f2d4a
--- /dev/null
+++ b/test/parallel/test-url-is-url.js
@@ -0,0 +1,11 @@
+// Flags: --expose-internals
+'use strict';
+
+require('../common');
+
+const { URL, parse } = require('url');
+const assert = require('assert');
+const { isURL } = require('internal/url');
+
+assert.strictEqual(isURL(new URL('https://www.nodejs.org')), true);
+assert.strictEqual(isURL(parse('https://www.nodejs.org')), false);