diff --git a/mix/Dockerfile b/mix/Dockerfile
index 29f75da..0ac50cc 100644
--- a/mix/Dockerfile
+++ b/mix/Dockerfile
@@ -8,7 +8,7 @@ RUN apk upgrade --update musl \
             gd-dev jpeg-dev libpng-dev libwebp-dev \
             elixir erlang-crypto erlang-eunit erlang-mnesia erlang-erts erlang-hipe \
             erlang-tools erlang-os-mon erlang-syntax-tools erlang-parsetools \
-            erlang-runtime-tools erlang-reltool \
+            erlang-runtime-tools erlang-reltool file \
  && rm -rf /var/cache/apk/*
 
 # Setup runtime environment