Southern Illinois scored the final four points of the first half and the first nine points of the second to go ahead 34-16. Indiana State never mounted a challenge from there as the Salukis extended their lead to as much as 23.
Desmar Jackson had 16 points, Olaniyan scored 12 and O'Brien added 11 for SIU (7-15, 3-6 Missouri Valley). O'Brien and Olaniyan each had 12 rebounds.
Southern Illinois made up for 2-of-12 3-point shooting by shooting 52 percent overall and 25 of 38 on free throws. Indiana State was only 11 of 22 at the free-throw line.