Missing cfg guard
diff --git a/src/macro_input.rs b/src/macro_input.rs
index 536ba9d..64a735e 100644
--- a/src/macro_input.rs
+++ b/src/macro_input.rs
@@ -53,6 +53,7 @@
     ));
 }
 
+#[cfg(feature = "printing")]
 mod printing {
     use super::*;
     use data::{Visibility, VariantData};