if c.SystemContext.BlockInfo.ForkVersion < 2 {
        jsonArgs = `{"who":"` + types.EncodeAddress(sender.ID()) + `", "amount":"` + balanceAdjustment.String() + `"}`
    } else {
        jsonArgs = `["` + types.EncodeAddress(sender.ID()) + `", {"_bignum":"` + balanceAdjustment.String() + `"}]`
    }