diff --git a/lib/Database/ez_mysqli.php b/lib/Database/ez_mysqli.php
index 90641b0..0d33835 100644
--- a/lib/Database/ez_mysqli.php
+++ b/lib/Database/ez_mysqli.php
@@ -291,7 +291,7 @@ public function query_prepared(string $query, array $param = null)
         $params = [];
         $types = \array_reduce(
             $param,
-            function ($string, &$arg) use (&$params) {
+            function ($string, $arg) use (&$params) {
                 $params[] = &$arg;
                 if (\is_float($arg))
                     $string .= 'd';