diff --git a/rups/src/lib.rs b/rups/src/lib.rs
index 2964e53..ea2e8a3 100644
--- a/rups/src/lib.rs
+++ b/rups/src/lib.rs
@@ -17,7 +17,7 @@ pub mod blocking;
 /// Reference: <https://networkupstools.org/docs/developer-guide.chunked/ar01s09.html>
 #[allow(dead_code)]
 #[macro_use]
-pub mod proto;
+pub(crate) mod proto;
 /// Async client implementation for NUT, using Tokio.
 #[cfg(feature = "async")]
 pub mod tokio;