diff --git a/Dockerfile b/Dockerfile
index 3728e97..0c91bda 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -19,6 +19,21 @@ WORKDIR /app
 RUN npm ci --omit=dev
 
 FROM public.ecr.aws/docker/library/node:20-alpine AS build-env
+
+# These have to be declared HERE, not only in development-dependencies-env:
+# build args do not cross stages, and this is the stage that runs `npm run
+# build`. Without them Vite inlines the fallbacks from app/routes/*.tsx --
+# https://api.t4t-gateway.com -- so an image built for anywhere else silently
+# drives production.
+ARG VITE_API_URL
+ENV VITE_API_URL=$VITE_API_URL
+
+ARG VITE_GOOGLE_CLIENT_ID
+ENV VITE_GOOGLE_CLIENT_ID=$VITE_GOOGLE_CLIENT_ID
+
+ARG VITE_COMMIT_SHA
+ENV VITE_COMMIT_SHA=$VITE_COMMIT_SHA
+
 COPY . /app/
 COPY --from=development-dependencies-env /app/node_modules /app/node_modules
 WORKDIR /app