Calling fail on a UTF-8 encoded string (in file) causes garbage to be printed

For example,

guerrilla@delta:/tmp/foo$ cat Test.hs 
module Main where

main :: IO ()
main =
    do
        putStrLn "μ"
        fail "μ"
guerrilla@delta:/tmp/foo$ ./Test 
μ
Test: user error (�)
guerrilla@delta:/tmp/foo$ ./Test 2>&1 | xxd
0000000: cebc 0a54 6573 743a 2075 7365 7220 6572  ...Test: user er
0000010: 726f 7220 28bc 290a                      ror (.).

Using either encodeString or writing it in escaped hexidecimal does work.