diff --git a/compat/json-exception-polyfill.php b/compat/json-exception-polyfill.php
index 8b93a038..cb30ed36 100644
--- a/compat/json-exception-polyfill.php
+++ b/compat/json-exception-polyfill.php
@@ -1,6 +1,6 @@
 <?php
 
-if (PHP_VERSION_ID < 70300) {
+if (PHP_VERSION_ID < 70300 && ! class_exists('JsonException')) {
     class JsonException extends Exception
     {
     }