diff --git a/classes/validator/Validator.class.php b/classes/validator/Validator.class.php
index 21da30572..36a94993a 100644
--- a/classes/validator/Validator.class.php
+++ b/classes/validator/Validator.class.php
@@ -264,7 +264,7 @@ class Validator
 				return in_array($value, $rule['test']);
 			case 'expr':
 				if(!$rule['func_test']) {
-					$rule['func_test'] = create_function('$a', 'return ('.preg_replace('/$$/', '$a', $rule['test']).');');
+					$rule['func_test'] = create_function('$a', 'return ('.preg_replace('/\$\$/', '$a', $rule['test']).');');
 				}
 				return $rule['func_test']($value);
 		}