Our problem \textsc{Mine Sweeper} is: given an undirected graph where some vertices have a natural number associated with them, decide whether there is a way to mark some of the non-numbered vertices such that the number in each numbered vertex is equal to the amount of its marked neighbours. We reduce \textsc{Dominating Set} problem to ours. \textsc{Dominating Set} is shown to be hard by \cite{GJ}.