diff --git a/Dockerfile b/Dockerfile
index 3a45043..0932d4e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -52,7 +52,7 @@ RUN mkdir -p /data && chown nextjs:nodejs /data
 
 COPY --from=proddeps --chown=nextjs:nodejs /app/node_modules ./node_modules
 COPY --from=builder  --chown=nextjs:nodejs /app/.next ./.next
-COPY --chown=nextjs:nodejs package.json next.config.ts ./
+COPY --chown=nextjs:nodejs package.json next.config.mjs ./
 COPY --chown=nextjs:nodejs public ./public
 # /api/autobuyer/status reads the version out of this manifest and the extension
 # reloads itself to match, so the folder has to travel with the server.
@@ -61,7 +61,7 @@ COPY --chown=nextjs:nodejs extension ./extension
 USER nextjs
 EXPOSE 3000
 
-HEALTHCHECK --interval=30s --timeout=5s --start-period=15s --retries=3 \
+HEALTHCHECK --interval=15s --timeout=10s --start-period=20s --retries=5 \
     CMD node -e "fetch('http://127.0.0.1:3000/api/autobuyer/status').then(r=>process.exit(r.ok?0:1)).catch(()=>process.exit(1))"
 
 CMD ["npm", "start"]
diff --git a/next.config.mjs b/next.config.mjs
new file mode 100644
index 0000000..5579de9
--- /dev/null
+++ b/next.config.mjs
@@ -0,0 +1,9 @@
+/** @type {import('next').NextConfig} */
+// Plain JS, not TypeScript: `next start` in the production image has no
+// devDependencies, and a .ts config makes Next stop and install TypeScript —
+// with yarn, into a read-only-by-intent node_modules — before it will boot.
+const nextConfig = {
+  serverExternalPackages: ['better-sqlite3'],
+};
+
+export default nextConfig;
diff --git a/next.config.ts b/next.config.ts
deleted file mode 100644
index 40988d5..0000000
--- a/next.config.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-import type { NextConfig } from "next";
-
-const nextConfig: NextConfig = {
-  serverExternalPackages: ['better-sqlite3'],
-};
-
-export default nextConfig;