diff --git a/client/vite.config.ts b/client/vite.config.ts
index f4ecd25..c1e650b 100644
--- a/client/vite.config.ts
+++ b/client/vite.config.ts
@@ -3,6 +3,13 @@ import preact from '@preact/preset-vite';
 import legacy from '@vitejs/plugin-legacy';
 import { resolve } from 'node:path';
 
+// The dev-server proxy target — same default (3000) as the server's own
+// `process.env.PORT ?? 3000` in server/src/index.ts. Override with
+// `WUTZ_SERVER_PORT` when running `dev:server` on a non-default port, e.g.:
+//   PORT=4000 pnpm dev:server
+//   WUTZ_SERVER_PORT=4000 pnpm dev:client
+const serverTarget = `http://localhost:${process.env.WUTZ_SERVER_PORT ?? 3000}`;
+
 export default defineConfig({
   plugins: [
     preact(),
@@ -24,9 +31,9 @@ export default defineConfig({
   server: {
     port: 5173,
     proxy: {
-      '/api': 'http://localhost:3000',
-      '/admin': 'http://localhost:3000',
-      '/healthz': 'http://localhost:3000',
+      '/api': serverTarget,
+      '/admin': serverTarget,
+      '/healthz': serverTarget,
     },
   },
 });