diff --git a/docker/app.Dockerfile b/docker/app.Dockerfile
index 7940024649..67eb5f02c7 100644
--- a/docker/app.Dockerfile
+++ b/docker/app.Dockerfile
@@ -69,11 +69,13 @@ ENV NEXT_TELEMETRY_DISABLED=1 \
     VERCEL_TELEMETRY_DISABLED=1 \
     DOCKER_BUILD=1
 
-# Provide dummy database URLs during image build so server code that imports @sim/db
-# can be evaluated without crashing. Runtime environments should override these.
+# Dummy values so next build can evaluate modules. Override at runtime.
 ARG DATABASE_URL="postgresql://user:pass@localhost:5432/dummy"
 ENV DATABASE_URL=${DATABASE_URL}
 
+ARG NEXT_PUBLIC_APP_URL="http://localhost:3000"
+ENV NEXT_PUBLIC_APP_URL=${NEXT_PUBLIC_APP_URL}
+
 # Per-platform cache id keeps arm64/amd64 SWC artifacts isolated.
 RUN --mount=type=cache,id=next-cache-${TARGETPLATFORM},target=/app/apps/sim/.next/cache \
     --mount=type=cache,id=turbo-cache-${TARGETPLATFORM},target=/app/.turbo \