diff --git a/src/liballoc/boxed.rs b/src/liballoc/boxed.rs
index b5c2fd7526da..c25f3eb8f175 100644
--- a/src/liballoc/boxed.rs
+++ b/src/liballoc/boxed.rs
@@ -71,6 +71,7 @@ use core::ptr::{self, NonNull, Unique};
 use core::task::{Context, Poll, Spawn, SpawnErrorKind, SpawnObjError};
 
 use raw_vec::RawVec;
+use pin::PinBox;
 use str::from_boxed_utf8_unchecked;
 
 /// A pointer type for heap allocation.
@@ -816,3 +817,10 @@ impl<'a, F: Future<Output = ()> + 'a> From<Box<F>> for LocalFutureObj<'a, ()> {
         LocalFutureObj::new(boxed)
     }
 }
+
+#[unstable(feature = "pin", issue = "49150")]
+impl<T: Unpin + ?Sized> From<PinBox<T>> for Box<T> {
+    fn from(pinned: PinBox<T>) -> Box<T> {
+        unsafe { PinBox::unpin(pinned) }
+    }
+}
diff --git a/src/liballoc/pin.rs b/src/liballoc/pin.rs
index 1b6ccae456ad..bacc13fa74ac 100644
--- a/src/liballoc/pin.rs
+++ b/src/liballoc/pin.rs
@@ -133,13 +133,6 @@ impl<T: ?Sized> From<Box<T>> for PinBox<T> {
     }
 }
 
-#[unstable(feature = "pin", issue = "49150")]
-impl<T: Unpin + ?Sized> From<PinBox<T>> for Box<T> {
-    fn from(pinned: PinBox<T>) -> Box<T> {
-        pinned.inner
-    }
-}
-
 #[unstable(feature = "pin", issue = "49150")]
 impl<T: ?Sized> Deref for PinBox<T> {
     type Target = T;