Unwanted ScreenPointToRay vertical offset

[minus10degrees (minus10degreesssssss)]

Hello, working on a tycoon placement system!
Sorry but I don’t know the exact words to explain this(bad english issue), so if you have an idea then tell me and I’ll change the title!

This is a piece of my code:

local function DoRaycast()
	local mPos = UserInputService:GetMouseLocation()
	local ray = camera:ScreenPointToRay(mPos.X, mPos.Y)
	raycast = workspace:Raycast(ray.Origin, ray.Direction.Unit * 128)
	
	if raycast ~= nil then
		mouseHit = CFrame.new(raycast.Position, raycast.Position + ray.Direction)
	else
		mouseHit = CFrame.new(ray.Origin + ray.Direction*129)
	end
	p.CFrame = mouseHit
end

Any help would be appreciated!

[SuperBlockUAlt (Block)]

ScreenPointToRay accounts for topbar inset and is offseted

While ViewportPointToRay does not account for topbar inset

Replace ScreenPointToRay to ViewportPointToRay

[OiiKaee]

local ray = camera:ScreenPointToRay(mPos.X, mPos.Y)

I often find that the offset of Y is due to the GUI offset.

local ray = camera:ScreenPointToRay(mPos.X, mPos.Y-50)

Or

local ray = camera:ScreenPointToRay(mPos.X, mPos.Y-36)

Often fixes this, just can’t remember if it’s negative or positive offset.

[SuperBlockUAlt (Block)]

UserInputService:GetMouseLocation() is calculated relative to top-left corner of the screen meaning negative Y is up while positive Y is down

[ys3741 (y_s)]

Probably because of the topbar like @SuperBlockUAlt said, his solution might work, I don’t know much about those functions, but I do know that there’s a difference between UIS:GetMousePosition() and (mouse.X, mouse.Y), so you can try using the mouse instead of UIS

[minus10degrees (minus10degreesssssss)]

Aha I got it. It seems I mistook ViewportToRay for the Screen thing.
i can’t test right now, so I’ll do it tomorrow and mark it as solution if it works. Thank you everyone for helping!