Dialyzer not compiling correctly

Thanks for popping in!

After a long time of waiting, it finally finished, but now I have the following warnings/errors:

Finding suitable PLTs
Checking PLT...
[:compiler, :elixir, :kernel, :logger, :stdlib]
PLT is up to date!
No :ignore_warnings opt specified in mix.exs and default does not exist.

Starting Dialyzer
[
  check_plt: false,
  init_plt: '/home/fl4m3/Workspace/elixir_and_otp_guidebook/dialyzer_playground/_build/dev/dialyxir_erlang-21.1_elixir-1.7.3_deps-dev.plt',
  files_rec: ['/home/fl4m3/Workspace/elixir_and_otp_guidebook/dialyzer_playground/_build/dev/lib/dialyzer_playground/ebin'],
  warnings: [:unknown]
]
** (UndefinedFunctionError) function Dialyxir.Project.filter_warnings/1 is undefined or private. Did you mean one of:

      * filter_legacy_warnings/1
      * filter_legacy_warnings/2
      * filter_warning?/1

Am I missing some config flag?

I am using the {:dialyxir, "~> 1.0.0-rc.4", only: [:dev], runtime: false}, perhaps it is not stable enough?