diff --git a/src/Generator/MCryptGenerator.php b/src/Generator/MCryptGenerator.php
index 943199f..706fd11 100644
--- a/src/Generator/MCryptGenerator.php
+++ b/src/Generator/MCryptGenerator.php
@@ -55,7 +55,8 @@ public function generate($byteCount)
     public static function isSupported()
     {
         $supported = false;
-        if (function_exists('mcrypt_create_iv')) {
+        if (function_exists('mcrypt_create_iv') &&
+            version_compare(phpversion(), '7.1', '<')) {
             $supported = true;
         }