Either I am misunderstanding something or there is an infelicity in the implementation of StdGen. The documentation on mkStdGen says that distinct arguments should be likely to produce distinct generators. This made me think that I would get a reasonable pseudo-random function to simulate n rolls of a die by using n to seed the random number generator: import System.Random roll :: Int -> String roll n = take n . randomRs ('1', '6') . mkStdGen $ n However, this produces a string beginning with a '6' for 0 <= n <= 53667. In fact the dependency of the first value on the seed seems to be far from random: map (\l -> (head l, length l)) . group . map (fst . randomR (1, 6) . mkStdGen) $ [0..25*53668+6] returns: [(6,53668),(5,53668),(4,53668),(3,53669),(2,53668),(1,53668),(6,53669),(5,53668),(4,53668),(3,53669),(2,53668),(1,53668),(6,53668),(5,53669),(4,53668),(3,53668),(2,53669),(1,53668),(6,53668),(5,53669),(4,53668),(3,53668),(2,53669),(1,53668),(6,53668)] The behaviour seems to be related to the length of the range. You get similar behaviour for ranges of length 2, 3, 6 and 9 for example, but not for 4, 5, 7 or 8. If it is relevant, I am using ghc version 7.6.3. Regards, Rob.