diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index 5e5d7b917209..46d3ccb9de52 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -899,6 +899,7 @@ impl<T> Generator for Box<T>
 
 /// A pinned, heap allocated reference.
 #[unstable(feature = "pin", issue = "0")]
+#[fundamental]
 pub struct PinBox<T: ?Sized> {
     inner: Box<T>,
 }
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index 792d71732e66..e960b5ae7582 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -1112,6 +1112,7 @@ pub unsafe fn unreachable() -> ! {
 /// safe to move a value out of a pinned reference unless the type of that
 /// value implements the `Unpin` trait.
 #[unstable(feature = "pin", issue = "0")]
+#[fundamental]
 pub struct Pin<'a, T: ?Sized + 'a> {
     inner: &'a mut T,
 }