diff --git a/src/private/mod.rs b/src/private/mod.rs
index 73355e4..24ea84b 100644
--- a/src/private/mod.rs
+++ b/src/private/mod.rs
@@ -1,8 +1,13 @@
-mod macros;
-
+#[cfg(serde_derive)]
 pub mod de;
+#[cfg(serde_derive)]
 pub mod ser;
 
+pub mod size_hint;
+
+// FIXME: #[cfg(doctest)] once https://github.com/rust-lang/rust/issues/67295 is fixed.
+pub mod doc;
+
 pub use lib::clone::Clone;
 pub use lib::convert::{From, Into};
 pub use lib::default::Default;