Partition wall supported by subfloor

I need to replace the subfloor in my bathroom, but I noticed the partition wall between the bathroom and the kitchen does not rest directly over one of the joists that run parallel to this wall. The plank subfloor is apparently all that prevents the sill plate from deflecting. The sink drain runs through the joist bay beneath this wall. What's the best way to replace the subfloor in this area? Would 2x4 blocking provide sufficient support for the wall?