diff --git a/middleware/rateLimiter.js b/middleware/rateLimiter.js
index 5c73bf0..7da69f9 100644
--- a/middleware/rateLimiter.js
+++ b/middleware/rateLimiter.js
@@ -1,6 +1,6 @@
 'use strict';
 
-const rateLimit = require('express-rate-limit');
+const { rateLimit, ipKeyGenerator } = require('express-rate-limit');
 
 function makeLimiter(max, windowMs, message) {
   return rateLimit({
@@ -69,7 +69,7 @@ const syncLimiter = rateLimit({
   max: 10,
   standardHeaders: 'draft-7',
   legacyHeaders: false,
-  keyGenerator: (req) => req.user?.id?.toString() || req.ip,
+  keyGenerator: (req) => req.user?.id?.toString() || ipKeyGenerator(req),
   handler(req, res) {
     res.status(429).json({ error: 'Too many sync requests. Please try again in 15 minutes.' });
   },