diff --git a/litellm/llms/vertex_ai/vertex_llm_base.py b/litellm/llms/vertex_ai/vertex_llm_base.py
index caf2022c1db..aa41af3287f 100644
--- a/litellm/llms/vertex_ai/vertex_llm_base.py
+++ b/litellm/llms/vertex_ai/vertex_llm_base.py
@@ -55,7 +55,7 @@ class VertexBase:
         # Tracks in-flight background refresh tasks to avoid duplicate refreshes.
         self._background_refresh_tasks: Dict[tuple, asyncio.Task] = {}
         # Protects the sync get_access_token refresh path.
-        self._sync_refresh_lock = threading.Lock()
+        self._sync_refresh_lock = threading.RLock()
 
     def get_vertex_region(self, vertex_region: Optional[str], model: str) -> str:
         import litellm