diff --git a/index.php b/index.php
index c3477e5..67de12d 100644
--- a/index.php
+++ b/index.php
@@ -29,7 +29,7 @@ class ConnectionManager {
         }
 }
 abstract class BaseModel {
-    protected static ISqlBase $sql = null;
+    protected static ?ISqlBase $sql = null;
     
     public static function Get(int $id) {
         static::Initialize();