diff --git a/src/lib.rs b/src/lib.rs
index f2c1a14..35411e3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 // Behind the feature gates
-#![cfg_attr(feature = "hw", feature(stdsimd))]
+#![cfg_attr(feature = "hw", feature(portable_simd))]
 #![cfg_attr(feature = "hw", feature(llvm_asm))]
+#![cfg_attr(feature = "hw", feature(stdarch_x86_rtm))]
 // FIXME: Baking still
 #![allow(dead_code)]
 #![allow(unused_imports)]
diff --git a/src/sync/atomics.rs b/src/sync/atomics.rs
index c389308..d9b6ccb 100644
--- a/src/sync/atomics.rs
+++ b/src/sync/atomics.rs
@@ -107,6 +107,13 @@ impl<T: Sized> AtomicBox<T> {
         let ptr = Arc::into_raw(Arc::new(new_val)) as *mut T;
         self.release(ptr);
     }
+
+    ///
+    /// Atomically replace the inner value with the given one.
+    pub fn replace(&self, new_val: T) {
+        let ptr = Arc::into_raw(Arc::new(new_val)) as *mut T;
+        self.release(ptr);
+    }
 }
 
 impl<T: Sized + PartialEq> PartialEq for AtomicBox<T> {