Gday, The project readme reccomends installing a version from hex.pm which is not published to hex.pm. The workaround is to specify the mix's dep explicitly to github with the version tag The example below seems to work if anyone else is affected by this: ``` # In mix.exs ... defp deps do [ {:slack, git: "https://github.com/BlakeWilliams/Elixir-Slack.git", tag: "v0.23.6"} ] end ``` Thank you for the effort put in to this library. Thanks!