Ikea ERIK cabinet third drawer locking mechanism

After I bought the Ikea ERIK with 3 drawers I was displeased about the fact that only 2 out of 3 drawers can be locked. To fix this I have made two little ledges you can screw onto the top drawer. This will prevent the top drawer from opening while the middle drawer is closed.

By then placing the drawer with the lock at the bottom of the cabinet the original lock prevents the bottom and middle drawer from opening. the middle drawer prevents the top drawer from opening, thus efficiently lockin