diff --git a/litellm/router.py b/litellm/router.py
index bfb7ab1561b..bf5f32f9c7b 100644
--- a/litellm/router.py
+++ b/litellm/router.py
@@ -14084,7 +14084,7 @@ class Router:
         )
 
         ## get model group RPM ##
-        model_group_cache: dict[str, int] | None = None
+        model_group_cache: dict[str, int] | None = None  # mutable-ok: incremented below
         if _any_deployment_has_rpm:
             dt = get_utc_datetime()
             current_minute = dt.strftime("%H-%M")