Hey guys! So, I was working on some cross-compiling, and found a bug (http://hackage.haskell.org/trac/ghc/ticket/7620) Eventually I found that the issue was with C CodeGen in general, and had nothing to do with ARM. I've attached the patch there, but it may be only part of a bigger problem. The rough problem came from two things: 1) -(-128 :: Int8) => -128 You can't negate the smallest int in an integer space because of how 2s compliment works. There aren't enough bits to store +128. 2) We have a number of operations that transform: | i < 0 = a + i => a - (negative i) And | i < 0 = a - i => a + (negative i) And the assumption is that any integer can be negated, but that's not true in exactly one case. So, for example, it could turn thing+-128 into thing--128 Which is not valid C. That (but for Int32) was what I was seeing, and causing me trouble building integer simple. So, that was the bug I had encountered, and I don't know how the GHC code works, I just trawled through until I found the line that was causing me trouble, but I just figured I'd remind people that not every integer can be negated, in case the same mistake is being done in other places.