diff --git a/dev.Dockerfile b/dev.Dockerfile
index 66bdfbed..d48d94b7 100644
--- a/dev.Dockerfile
+++ b/dev.Dockerfile
@@ -5,6 +5,7 @@ ARG DEV_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEB
 
 FROM ${DEV_IMAGE}
 
+ARG MIX_ENV=dev
 ARG TARGETPLATFORM
 RUN echo "Building for ${TARGETPLATFORM:?}"
 
@@ -58,8 +59,8 @@ RUN chmod +x ./docker-run.dev.sh
 
 # Install Elixir deps
 # RUN mix archive.install github hexpm/hex branch latest
-RUN mix deps.get
-RUN mix deps.compile
+RUN MIX_ENV=${MIX_ENV} mix deps.get
+RUN MIX_ENV=${MIX_ENV} mix deps.compile
 # Gives us iex shell history
 ENV ERL_AFLAGS="-kernel shell_history enabled"
 
diff --git a/docker-compose.ci.yml b/docker-compose.ci.yml
index d4f4d6fb..5fb6d8c8 100644
--- a/docker-compose.ci.yml
+++ b/docker-compose.ci.yml
@@ -4,6 +4,8 @@ services:
     build:
       context: .
       dockerfile: dev.Dockerfile
+      args:
+        MIX_ENV: test
     environment:
       - MIX_ENV=test
     volumes: