diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index 2db55508ad546..1b586c3e5fe30 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -97,7 +97,7 @@ pub trait Sized {
 /// Types that can be "unsized" to a dynamically-sized type.
 ///
 /// For example, the sized array type `[i8; 2]` implements `Unsize<[i8]>` and
-/// `Unsize<fmt::Debug>`.
+/// `Unsize<dyn fmt::Debug>`.
 ///
 /// All implementations of `Unsize` are provided automatically by the compiler.
 ///