Android Checkable Menu Item

I have the following menu layout in my Android app:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/item1" 
          android:titleCondensed="Options"
          android:title="Highlight Options" 
          android:icon="@android:drawable/ic_menu_preferences" />

   <item android:id="@+id/item2" 
         android:titleCondensed="Persist"
         android:title="Persist" 
         android:icon="@android:drawable/ic_menu_preferences" 
         android:checkable="true" />
</menu>

My problem is that the second menu item doesn't appear to be "checkable" when I run my app in the Android emulator. There should be a green tick about the item, right? To indicate that its checkable.

Am I doing something wrong?