diff --git a/Dockerfile b/Dockerfile
index e20016dc0..0e87096d2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,7 +4,7 @@ WORKDIR /app
 
 # --- Install + Build in one stage ---
 FROM base AS builder
-ARG CACHE_BUST=2
+ARG CACHE_BUST=3
 COPY . .
 RUN pnpm install --no-frozen-lockfile
 ENV NEXT_TELEMETRY_DISABLED=1
@@ -14,9 +14,11 @@ ENV NEXT_TELEMETRY_DISABLED=1
 ARG NEXT_PUBLIC_SITE_URL=https://myeasycms.de
 ARG NEXT_PUBLIC_SUPABASE_URL=http://localhost:8000
 ARG NEXT_PUBLIC_SUPABASE_PUBLIC_KEY
+ARG NEXT_PUBLIC_DEFAULT_LOCALE=de
 ENV NEXT_PUBLIC_SITE_URL=${NEXT_PUBLIC_SITE_URL}
 ENV NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL}
 ENV NEXT_PUBLIC_SUPABASE_PUBLIC_KEY=${NEXT_PUBLIC_SUPABASE_PUBLIC_KEY}
+ENV NEXT_PUBLIC_DEFAULT_LOCALE=${NEXT_PUBLIC_DEFAULT_LOCALE}
 RUN pnpm --filter web build
 
 # --- Run ---
diff --git a/docker-compose.yml b/docker-compose.yml
index 8d5cebab6..cf6cc5898 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -321,8 +321,10 @@ services:
     environment:
       NODE_ENV: production
       NEXT_PUBLIC_SITE_URL: ${SITE_URL:-http://localhost:3000}
-      # NEXT_PUBLIC_ vars are baked at build time — runtime values only apply
-      # to middleware/API routes. Don't override with Docker-internal URLs.
+      # Must match the build-time value — server code reads from process.env
+      NEXT_PUBLIC_SUPABASE_URL: ${API_EXTERNAL_URL:-http://localhost:8000}
+      NEXT_PUBLIC_SUPABASE_PUBLIC_KEY: ${SUPABASE_ANON_KEY}
+      NEXT_PUBLIC_DEFAULT_LOCALE: de
       SUPABASE_SECRET_KEY: ${SUPABASE_SERVICE_ROLE_KEY}
       SUPABASE_DB_WEBHOOK_SECRET: ${DB_WEBHOOK_SECRET:-webhooksecret}
       EMAIL_SENDER: ${EMAIL_SENDER:-noreply@myeasycms.de}