I just compiled elxir lang from source and it works. So it seems that we need to update the elixir version. i have used the github devel master version. ./elixir --version Erlang/OTP 20 [erts-9.3.3.6] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false] Elixir 1.9.0-dev (da3c42647) (compiled with Erlang/OTP 20)