How to randomize part orientation?

I am using tweenservice to rotate a part when a specific action occurs. The part does rotate, but it rotates in the same direction instead of random directions each time. How do I properly randomize orientation?

local tweeninfo = TweenInfo.new(1)
ts = game:GetService("TweenService")
local goal = {}
goal.Size = Vector3.new(0, 0, 0)
goal.Orientation = Vector3.new(math.random(-90,90),math.random(-90,90),math.random(-90,90))