diff --git a/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraintValidator.php b/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraintValidator.php
index 6811bf309c..409df6dd89 100644
--- a/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraintValidator.php
+++ b/core/modules/link/src/Plugin/Validation/Constraint/LinkExternalProtocolsConstraintValidator.php
@@ -47,7 +47,7 @@ public function validate($value, Constraint $constraint) {
         // Validates a domain if the needed PHP extensions are available for
         // Punycode conversion.
         if (function_exists('idn_to_ascii')) {
-          $hostname = idn_to_ascii($hostname);
+          $hostname = idn_to_ascii($hostname, 0, INTL_IDNA_VARIANT_UTS46);
           $is_invalid_url = !UrlHelper::isValid($hostname);
         }
         else {