diff --git a/semantic_router/index/pinecone.py b/semantic_router/index/pinecone.py
index dd0ac671..60ada2e3 100644
--- a/semantic_router/index/pinecone.py
+++ b/semantic_router/index/pinecone.py
@@ -654,7 +654,7 @@ async def _async_fetch_metadata(self, vector_id: str) -> dict:
         }
 
         if self.namespace:
-            params["namespace"] = self.namespace
+            params["namespace"] = [self.namespace]
 
         headers = {
             "Api-Key": self.api_key,