Incentive Stock Options (ISO) maxed at 99,999

I have more than 200K shares (worth pennies per share) of a small company that I would like to enter via Turbotax. But it seems to have max out at 99,999 for "Number of Shares Transferred" (Box 5 of Form 3921) in "Enter Your Purchase Information" screen. Why is this? And how can I enter a number greater than 100K? Why is there this low artificial limit?