diff --git a/EmailValidator/Validation/DNSCheckValidation.php b/EmailValidator/Validation/DNSCheckValidation.php
index 207fc73..da13253 100644
--- a/EmailValidator/Validation/DNSCheckValidation.php
+++ b/EmailValidator/Validation/DNSCheckValidation.php
@@ -21,7 +21,7 @@ class DNSCheckValidation implements EmailValidation
 
     public function __construct()
     {
-        if (!extension_loaded('intl')) {
+        if (!function_exists('idn_to_ascii')) {
             throw new \LogicException(sprintf('The %s class requires the Intl extension.', __CLASS__));
         }
     }
diff --git a/composer.json b/composer.json
index 5423e9f..510dcd4 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,8 @@
   ],
   "require":      {
     "php": ">= 5.5",
-    "doctrine/lexer": "^1.0.1"
+    "doctrine/lexer": "^1.0.1",
+    "symfony/polyfill-intl-idn": "^1.10"
   },
   "require-dev" :   {
     "satooshi/php-coveralls": "^1.0.1",