diff --git a/zerver/middleware.py b/zerver/middleware.py
index c23924f92b..c83465797f 100644
--- a/zerver/middleware.py
+++ b/zerver/middleware.py
@@ -334,8 +334,11 @@ class RateLimitMiddleware(object):
     def process_exception(self, request, exception):
         # type: (HttpRequest, Exception) -> HttpResponse
         if isinstance(exception, RateLimited):
-            resp = json_error(_("API usage exceeded rate limit, try again in %s secs") % (
-                              request._ratelimit_secs_to_freedom,), status=429)
+            resp = json_error(
+                _("API usage exceeded rate limit"),
+                data={'retry-after': request._ratelimit_secs_to_freedom},
+                status=429
+            )
             resp['Retry-After'] = request._ratelimit_secs_to_freedom
             return resp
 
diff --git a/zerver/tests/test_external.py b/zerver/tests/test_external.py
index dbab2592ab..75145a508c 100644
--- a/zerver/tests/test_external.py
+++ b/zerver/tests/test_external.py
@@ -112,9 +112,9 @@ class RateLimitTests(ZulipTestCase):
         self.assertEqual(result.status_code, 429)
         json = ujson.loads(result.content)
         self.assertEqual(json.get("result"), "error")
-        self.assertIn("API usage exceeded rate limit, try again in", json.get("msg"))
+        self.assertIn("API usage exceeded rate limit", json.get("msg"))
+        self.assertEqual(json.get('retry-after'), 0.5)
         self.assertTrue('Retry-After' in result)
-        self.assertIn(result['Retry-After'], json.get("msg"))
         self.assertEqual(result['Retry-After'], '0.5')
 
         # We actually wait a second here, rather than force-clearing our history,