Couldn't match type ‘IO’ with ‘[]’

I wrote a function to generate two random numbers, which I then pass to a different function to use them there. The code for this is:

randomIntInRange :: (Int, Int, Int, Int) -> Board
randomIntInRange (min,max,min2,max2) = do r <- randomRIO (min, max)
                                          r2 <- randomRIO (min2, max2)
                                          randomCherryPosition (r, r2)

And the function this function calls in its 'do' block is:

randomCherryPosition :: (Int, Int) -> Board
randomCherryPosition (x, y) = initialBoard & element y . element x .~ C

Where initialBoard is a list of lists and C is a predefined data type. I am using lens to change values inside the list. Running this gives me the error:

Couldn't match type ‘IO’ with ‘[]’
      Expected type: [Int]
        Actual type: IO Int

for both r and r2 lines. I have absolutely no idea what is going on here, or what i'm doing wrong, so I would greatly appreciate any help.