Allocating aligned memory?

In GHC, how can I allocate a chunk of memory aligned to some block size (say, 512 or 1024 bytes)? I tried to specify it in the "alignment" method in the Storable typeclass, but that does not seem to work. Is Storable.alignment really used in GHC? If so, is there a code example that allocates aligned memory in this way? For the moment I am using the C function memalign() like this: foreign import ccall "static stdlib.h" memalign :: CInt -> CInt -> IO (Ptr CChar) .... do ptr <- memalign alignment size fptr <- newForeignPtr finalizerFree ptr Is it safe to do so? Thanks, Peng