diff --git a/src/DeepCopy/DeepCopy.php b/src/DeepCopy/DeepCopy.php
index <HASH>..<HASH> 100644
--- a/src/DeepCopy/DeepCopy.php
+++ b/src/DeepCopy/DeepCopy.php
@@ -140,8 +140,8 @@ class DeepCopy
             return $var;
         }
 
-        // PHP 8.1 Enum
-        if (function_exists('enum_exists') && enum_exists($var::class)) {
+        // Enum
+        if (PHP_VERSION_ID >= 80100 && enum_exists($var::class)) {
             return $var;
         }
enum_exists may have been manually declared on lower PHP versions, use strict PHP version check