diff --git a/chul/serializers.py b/chul/serializers.py
index c8b5db02..e347d6fc 100755
--- a/chul/serializers.py
+++ b/chul/serializers.py
@@ -123,7 +123,7 @@ def buffer_updates(
                 health_unit=chu_instance,
                 is_approved=False, is_rejected=False)
             
-            update = chu_updates[-1] if chu_updates.__len__() > 0 else None
+            update = chu_updates[chu_updates.__len__() - 1] if chu_updates.__len__() > 0 else None
 
             if update is None:
                 raise ChuUpdateBuffer.DoesNotExist