diff --git a/src/libcore/clone.rs b/src/libcore/clone.rs
index 629c197e3769..eb101fc72fd9 100644
--- a/src/libcore/clone.rs
+++ b/src/libcore/clone.rs
@@ -219,7 +219,7 @@ mod impls {
         }
     }
 
-    // Shared references can be cloned, but mutable references *cannot*!
+    /// Shared references can be cloned, but mutable references *cannot*!
     #[stable(feature = "rust1", since = "1.0.0")]
     impl<T: ?Sized> Clone for &T {
         #[inline]
@@ -228,7 +228,7 @@ mod impls {
         }
     }
 
-    // Shared references can be cloned, but mutable references *cannot*!
+    /// Shared references can be cloned, but mutable references *cannot*!
     #[stable(feature = "rust1", since = "1.0.0")]
     #[cfg(not(bootstrap))]
     impl<T: ?Sized> !Clone for &mut T {}
diff --git a/src/libcore/marker.rs b/src/libcore/marker.rs
index 2b908f07af8d..549f80de36aa 100644
--- a/src/libcore/marker.rs
+++ b/src/libcore/marker.rs
@@ -87,7 +87,7 @@ impl<T: ?Sized> !Send for *mut T {}
     message = "the size for values of type `{Self}` cannot be known at compilation time",
     label = "doesn't have a size known at compile-time",
     note = "to learn more, visit <https://doc.rust-lang.org/book/\
-          ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>"
+            ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait>"
 )]
 #[fundamental] // for Default, for example, which requires that `[T]: !Default` be evaluatable
 #[cfg_attr(not(bootstrap), rustc_specialization_trait)]
@@ -790,7 +790,7 @@ mod copy_impls {
     #[stable(feature = "rust1", since = "1.0.0")]
     impl<T: ?Sized> Copy for *mut T {}
 
-    // Shared references can be copied, but mutable references *cannot*!
+    /// Shared references can be copied, but mutable references *cannot*!
     #[stable(feature = "rust1", since = "1.0.0")]
     impl<T: ?Sized> Copy for &T {}
 }