IPFW (12-11, 5-5 Summit) was down two with 4:02 left in the first when the Mastodons went on a 9-3 run to close the half and led 32-28 at the break.
The Jackrabbits tied it back up at 42 on George Marshall's 3-pointer 6 1/2 minutes into the second, but Michael Calder replied with a pair of 3-pointers to put IPFW up seven. Back-to-back-to-back treys by Isaiah McCray, Joe Edwards and Max Landis made it an 11-point game with 4:31 left and IPFW made 10 straight free throws at the end to seal it.
Landis finished with 19 points, McCray had 14 - with four 3-pointers - and Edwards added 12.
South Dakota State (17-8, 8-3 Summit) was led by Deondra Parks with 24 points and seven rebounds. Jake Bittle added 18.