diff --git a/lib/checkbox_icon_formfield.dart b/lib/checkbox_icon_formfield.dart
index 5880d36..e413d7e 100644
--- a/lib/checkbox_icon_formfield.dart
+++ b/lib/checkbox_icon_formfield.dart
@@ -8,7 +8,7 @@ class CheckboxIconFormField extends FormField<bool> {
     FormFieldSetter<bool>? onSaved,
     bool initialValue = false,
     ValueChanged<bool>? onChanged,
-    AutovalidateMode autovalidateMode,
+    AutovalidateMode? autovalidateMode,
     bool enabled = true,
     IconData trueIcon = Icons.check,
     IconData falseIcon = Icons.check_box_outline_blank,
diff --git a/lib/checkbox_list_tile_formfield.dart b/lib/checkbox_list_tile_formfield.dart
index 9ba1866..ff3e0ca 100644
--- a/lib/checkbox_list_tile_formfield.dart
+++ b/lib/checkbox_list_tile_formfield.dart
@@ -10,7 +10,7 @@ class CheckboxListTileFormField extends FormField<bool> {
     FormFieldValidator<bool>? validator,
     bool initialValue = false,
     ValueChanged<bool>? onChanged,
-    AutovalidateMode autovalidateMode,
+    AutovalidateMode? autovalidateMode,
     bool enabled = true,
     bool dense = false,
     Color? errorColor,