Malphite's ult slowing down

when cast ult in mal, he will slow down when selecting the end point at middle of a wall (while mal cant travel through, which means mal will beat up against the wall), he will travel way slower than he should be. i think the reason is due that the distance count is furhter since the end point chosen is in the middle of a wall while the actual distance is smaller (the actual distance is from the start point to the point right at the edge of the wall) and becasue the estimate time travel is calculated as mal's traveling the further distance thus the actual speed is down. Hope to fix it. thx