[Haskell-cafe] Stack overflow in simple code with getStdRandom / randomR (GHC)

The following three-liner creates a stack overflow (on my machine, MacOS), and I'm a bit puzzled as to why:

import System.Random

main = do mapM (const (getStdRandom (randomR (0, 50000::Int)))) [0..10000000]

botanix:~ stolz$ ./a.out Stack space overflow: current size 8388608 bytes. Use `+RTS -Ksize -RTS' to increase it. Yes, the list is quite long, but somehow I'd expected mapM to chug slowly along...printing "Hello World" doesn't create a stack overflow either, after all. My Haskell-foo has become a bit rusty, but I was wondering where I am missing a point or two here (and I couldn't find the correct profiler incantation that would give me more than a big black blob for the main-CAF). GHC is 6.12.3 on MacOS. Cheers, Volker