turtle.compare() always returns true

I am using the compare() function but can never get a 'false' value. I've googled around and have been only able to find bug reports specifying previous versions, in which it was stated that bug had been fixed. Am I doing something wrong or is this a known bug?

MC ver 1.6.4
CC ver 1.63 (official)

while true do
	if turtle.detect() then
		print(turtle.compare())
	end
end

So to be clear, you're saying that no matter what block you put in the turtle's selected inventory slot, and no matter what block is placed directly in front of the turtle, "turtle.compare()" will return true?

Are other mods in play? In particular, Bukkit or MCPC+…?