diff --git a/src/gen/fold.rs b/src/gen/fold.rs
index c6fb1a3..60935a9 100644
--- a/src/gen/fold.rs
+++ b/src/gen/fold.rs
@@ -30,6 +30,8 @@
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: index.html
+///
+/// *This trait is available if Syn is built with the `"fold"` feature.*
 pub trait Fold {
 # [ cfg ( any ( feature = "full" , feature = "derive" ) ) ]
 fn fold_abi(&mut self, i: Abi) -> Abi { fold_abi(self, i) }
diff --git a/src/gen/visit.rs b/src/gen/visit.rs
index b06009a..3fcf09c 100644
--- a/src/gen/visit.rs
+++ b/src/gen/visit.rs
@@ -28,6 +28,8 @@
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: index.html
+///
+/// *This trait is available if Syn is built with the `"visit"` feature.*
 pub trait Visit<'ast> {
 # [ cfg ( any ( feature = "full" , feature = "derive" ) ) ]
 fn visit_abi(&mut self, i: &'ast Abi) { visit_abi(self, i) }
diff --git a/src/gen/visit_mut.rs b/src/gen/visit_mut.rs
index 2c4cabe..94a7449 100644
--- a/src/gen/visit_mut.rs
+++ b/src/gen/visit_mut.rs
@@ -29,6 +29,8 @@
 /// See the [module documentation] for details.
 ///
 /// [module documentation]: index.html
+///
+/// *This trait is available if Syn is built with the `"visit-mut"` feature.*
 pub trait VisitMut {
 # [ cfg ( any ( feature = "full" , feature = "derive" ) ) ]
 fn visit_abi_mut(&mut self, i: &mut Abi) { visit_abi_mut(self, i) }