diff --git a/extern/sector-storage/stores/http_handler.go b/extern/sector-storage/stores/http_handler.go
index a4c0480d4..3e3468470 100644
--- a/extern/sector-storage/stores/http_handler.go
+++ b/extern/sector-storage/stores/http_handler.go
@@ -116,9 +116,16 @@ func (handler *FetchHandler) remoteGetSector(w http.ResponseWriter, r *http.Requ
 		w.WriteHeader(500)
 		return
 	}
+	if !stat.IsDir() {
+		defer func() {
+			if err := rd.(*os.File).Close(); err != nil {
+				log.Errorf("closing source file: %+v", err)
+			}
+		}()
+	}
 
 	w.WriteHeader(200)
-	if _, err := io.Copy(w, rd); err != nil { // TODO: default 32k buf may be too small
+	if _, err := io.CopyBuffer(w, rd, make([]byte, CopyBuf)); err != nil {
 		log.Errorf("%+v", err)
 		return
 	}