diff --git a/packages/example/src/todo/Todo.tsx b/packages/example/src/todo/Todo.tsx
index 4f49b9f..573bef2 100644
--- a/packages/example/src/todo/Todo.tsx
+++ b/packages/example/src/todo/Todo.tsx
@@ -76,10 +76,10 @@ export const Todo = Component.make(function* Todo(props: TodoProps) {
                         </IconButton>
 
                         <IconButton
-                            disabled={props.index >= todosSize}
+                            disabled={props.index >= todosSize - 1}
                             onClick={() => Runtime.runSync(runtime)(
                                 Ref.updateSome(state.ref, todos => Option.gen(function*() {
-                                    if (props.index >= Chunk.size(todos))
+                                    if (props.index >= Chunk.size(todos) - 1)
                                         return yield* Option.none()
 
                                     const toSwapIndex = props.index + 1