Reversing stock adjustment journal in weighted average cost

Hi Experts,

A stock adjustment journal has been posted as receipt (with cost price as 1) since there was some error in item load. Now since the item load is done, the adjustment journal needs to be reversed. However when I tried to post the reversing journal with negative quantity, the cost price is getting updated from item master and system is not allowing to change it since the costing method is weighted average cost. 

Please help me with a solution.

Thanks in advance

Khushi