How to make a maximum speed limit?

So I have script that increases the characters speed while they run, but I want to have a maximum speed that it cant go above.

Script:

local Running = false

game.Players.PlayerAdded:Connect(function(player)
    repeat wait() until player.Character
    local Humanoid = player.Character:WaitForChild("Humanoid")
        if newState == Enum.HumanoidStateType.Running or 
            newState == Enum.HumanoidStateType.RunningNoPhysics then
            if not Running then Running = true
                repeat wait(0.1)
                Humanoid.WalkSpeed = Humanoid.WalkSpeed + .8
                until not Running
                Humanoid.WalkSpeed = 20
            end
         elseif not Enum.HumanoidStateType.Jumping then
            Running = false
        end
    end)
end)