diff --git a/lib/src/models/config/toolbar/buttons/select_header_style_dropdown_button_configurations.dart b/lib/src/models/config/toolbar/buttons/select_header_style_dropdown_button_configurations.dart
index 8aafcc78..ab1e2203 100644
--- a/lib/src/models/config/toolbar/buttons/select_header_style_dropdown_button_configurations.dart
+++ b/lib/src/models/config/toolbar/buttons/select_header_style_dropdown_button_configurations.dart
@@ -49,7 +49,7 @@ class QuillToolbarSelectHeaderStyleDropdownButtonOptions
   ///   Attribute.header,
   /// ]
   /// ```
-  final List<Attribute<int>>? attributes;
+  final List<Attribute<int?>>? attributes;
 
   QuillToolbarSelectHeaderStyleDropdownButtonOptions copyWith({
     ValueChanged<String>? onSelected,