diff --git a/lib/storage.ts b/lib/storage.ts
index 5c25cda..b3eacd6 100644
--- a/lib/storage.ts
+++ b/lib/storage.ts
@@ -185,7 +185,7 @@ function partitionPathFromSegmentId(id: string): string {
 }
 
 function buildPartitionedFilePath(prefix: string, id: string): string {
-  return path.join(DATA_DIR, partitionPathFromSegmentId(id), `${prefix}-${id}.parquet`);
+  return path.join(DATA_DIR, prefix, partitionPathFromSegmentId(id), `${prefix}-${id}.parquet`);
 }
 
 function buildVehicleFile(id: string): string {