This is very close, so close that yesterday the Defence Secretary Philip Hammond wrote to potential Tory rebels asking them not to hand Labour this victory.
Today, the MoD has offered a concession, it says it will bring in an annual report to Parliament on the state of the reserves but I'm not sure it's going to be enough to buy-off many rebels.
What they want is a report at the end of this process that they can vote on and they want to be able to hold up the whole thing if they don't think it's working.
There are a lot of people here who are concerned that the regular army has been run down before the reserve force has been built up and they're not all convinced by Hammond's reassurances that he will get the number of reserves he needs in place.
It's going to be an interesting afternoon