diff --git a/examples/todos-flow/src/types/index.js b/examples/todos-flow/src/types/index.js
index 64ccc5ccd8..d4c33a4f4f 100644
--- a/examples/todos-flow/src/types/index.js
+++ b/examples/todos-flow/src/types/index.js
@@ -6,9 +6,9 @@ export type Id = number;
 export type Text = string;
 
 export type Todo = {
-  id: Id,
-  text: Text,
-  completed: boolean
+  +id: Id,
+  +text: Text,
+  +completed: boolean
 };
 
 export type VisibilityFilter =
@@ -20,14 +20,14 @@ export type VisibilityFilter =
 export type Todos = Array<Todo>;
 
 export type State = {
-  todos: Todos,
-  visibilityFilter: VisibilityFilter
+  +todos: Todos,
+  +visibilityFilter: VisibilityFilter
 };
 
 export type Action =
-    { type: 'ADD_TODO', id: Id, text: Text }
-  | { type: 'TOGGLE_TODO', id: Id }
-  | { type: 'SET_VISIBILITY_FILTER', filter: VisibilityFilter }
+    { type: 'ADD_TODO', +id: Id, +text: Text }
+  | { type: 'TOGGLE_TODO', +id: Id }
+  | { type: 'SET_VISIBILITY_FILTER', +filter: VisibilityFilter }
   ;
 
 export type Store = ReduxStore<State, Action>;