diff --git a/src/lib/isURL.js b/src/lib/isURL.js
index 8ae971ed6..96ba6dc44 100644
--- a/src/lib/isURL.js
+++ b/src/lib/isURL.js
@@ -120,8 +120,15 @@ export default function isURL(url, options) {
         ? after_colon
         : after_colon.substring(0, first_slash_position);
       const at_position = before_slash.indexOf('@');
+      const is_host_with_port = /^[0-9]+$/.test(before_slash);
 
-      if (at_position !== -1) {
+      if (is_host_with_port) {
+        if (options.require_protocol) {
+          return false;
+        }
+
+        // Don't consume the colon; let host/port parsing handle it later.
+      } else if (at_position !== -1) {
         const before_at = before_slash.substring(0, at_position);
         const valid_auth_regex = /^[a-zA-Z0-9\-_.%:]*$/;
         const is_valid_auth = valid_auth_regex.test(before_at);
diff --git a/test/validators.test.js b/test/validators.test.js
index 5196c6fe9..9db1f1745 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -499,6 +499,7 @@ describe('Validators', () => {
         'localhost',
         'localhost:3000',
         'service-name:8080',
+        'my-3272-service:9000',
         'https://localhost',
         'http://localhost:3000',
         'http://service-name:8080',