diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f67e1d1a..75966d25 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
       - name: Docker Login
         run: echo "$DOCKERHUB_TOKEN" | docker login --username "$DOCKERHUB_USERNAME" --password-stdin
       - name: Run build
-        run: earthly --ci +ci
+        run: earthly --ci --build-arg MIX_ENV=dev +ci
 
   test:
     runs-on: ubuntu-latest
@@ -34,7 +34,7 @@ jobs:
       - name: Docker Login
         run: echo "$DOCKERHUB_TOKEN" | docker login --username "$DOCKERHUB_USERNAME" --password-stdin
       - name: Run build
-        run: earthly -P --ci +test
+        run: earthly -P --ci --build-arg MIX_ENV=test +test
 
   build-prod:
     runs-on: ubuntu-latest
@@ -48,5 +48,5 @@ jobs:
       - name: Docker Login
         run: echo "$DOCKERHUB_TOKEN" | docker login --username "$DOCKERHUB_USERNAME" --password-stdin
       - name: Run build
-        run: earthly -P --ci --push --build-arg GITHUB_REPO=${{ github.repository }} +docker
+        run: earthly -P --ci --push --build-arg MIX_ENV=prod --build-arg GITHUB_REPO=${{ github.repository }} +docker
 
diff --git a/Earthfile b/Earthfile
index 557779af..2f5b7d52 100644
--- a/Earthfile
+++ b/Earthfile
@@ -4,6 +4,7 @@ deps:
   ARG ELIXIR=1.16.0
   ARG OTP=26.1.2
   ARG ALPINE_VERSION=3.18.4
+  ARG MIX_ENV=test
   FROM hexpm/elixir:${ELIXIR}-erlang-${OTP}-alpine-${ALPINE_VERSION}
   RUN apk update --no-cache
   RUN apk add --no-cache build-base gcc git curl