Mid Lease Rent increase?

[Mike Landry]

I am buying a house with a renter currently in it.  He originally was going to move out but now wants to stay for another 5 months.  I want to give it to him at his current price for 2 months and then raise the rent $100 starting month 3.  This would still have him under market by 100 to 200.  Does anyone see any legal problems with this?

Would I be best to just sign a 2 month lease and then a new one afterwards?

I think he is concerned I am going to force him out and not honor what I told him I will do. 

Thanks!