How can I fit a bolt to this door frame?

[Homervanderjazz]

So I have a 17 month old who is into everything.. I have fitted necked bolts to the outside of a few doors. However, on the inside of the doors the door frame is curved, please see picture. Now without getting a joiner or locksmith is there any easy way to fit some sort of bolt to such a frame? Thanks

 

[JohnD]

Rack bolt (mortice bolt)

 

[Mikefromlondon]

You could simply use hook and eye type fasteners thing at higher level, don't need elaborate carpentry. like this : http://www.ebay.co.uk/itm/3-4-Long-...hash=item4882b42c19:m:mQQ9RD_F9M0ye7bra-I6bWA

 

[Homervanderjazz]

Thanks folks