diff --git a/httpstaticserver.go b/httpstaticserver.go
index 7e946a7..06be457 100644
--- a/httpstaticserver.go
+++ b/httpstaticserver.go
@@ -251,11 +251,14 @@ func (s *HTTPStaticServer) hUploadOrMkdir(w http.ResponseWriter, req *http.Reque
 	}
 	// Note: very large size file might cause poor performance
 	// _, copyErr = io.Copy(dst, file)
+
 	// use sync.Pool caching buf to reduce gc ratio
-	var bufPtr = &sync.Pool{
+	bufPool := sync.Pool{
 		New: func() interface{} { return make([]byte, 32*1024) },
 	}
-	_, copyErr = io.CopyBuffer(dst, file, bufPtr.Get().([]byte))
+	buf := bufPool.Get().([]byte)
+	_, copyErr = io.CopyBuffer(dst, file, buf)
+	defer bufPool.Put(&buf)
 	dst.Close()
 	// }
 	if copyErr != nil {