Indemnity clause in a Deed of Assignment

Dear One, I am on behalf of non-resident friend selling a piece of land which he bought from a family that owned it about 20 years ago. The land has a dilapidated building on it. It is one of several house located in a suburb part of Lagos Nigeria called Aboru. The neighbouhood is fully occupied but the street housing about two dozens of houses is normally water logged during the raining season and it is adjacent to a canal. My friend does not intend to develop the land and so he has asked me to sell it. In the draft Deed of assignment prepared by the purchaser is the following clause: "The ASSIGNOR will at all times thereof save and keep the ASSIGNEE and his Assigns indemnified from and against all Estate encumbrances, proceedings, cost, claims, expenses, liabilities, whatsoever arising from any defect-in-title in relation to the Land" My requests: 1. A modification of the above clause to limit the sellers' indemnity to costs, expenses, claims etc arising from claimants of superior title and exclude losses that may arise from possible future acquisition by the government. I am assuming that the clause as drafted exposes my friend to unlimited claims. Many thanks