diff --git a/library/vendor/Zend/Validate/File/Upload.php b/library/vendor/Zend/Validate/File/Upload.php
index 24a48d1ff..b86c1c7ea 100644
--- a/library/vendor/Zend/Validate/File/Upload.php
+++ b/library/vendor/Zend/Validate/File/Upload.php
@@ -159,7 +159,7 @@ class Zend_Validate_File_Upload extends Zend_Validate_Abstract
      */
     public function isValid($value, $file = null)
     {
-        $this->_messages = null;
+        $this->_messages = [];
         if (array_key_exists($value, $this->_files)) {
             $files[$value] = $this->_files[$value];
         } else {