diff --git a/rust/kernel/alloc/box_ext.rs b/rust/kernel/alloc/box_ext.rs
index 829cb1c1cf9e..9f1c1c489189 100644
--- a/rust/kernel/alloc/box_ext.rs
+++ b/rust/kernel/alloc/box_ext.rs
@@ -21,8 +21,10 @@ pub trait BoxExt<T>: Sized {
 
 impl<T> BoxExt<T> for Box<T> {
     fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
-        let b = <Self as BoxExt<_>>::new_uninit(flags)?;
-        Ok(Box::write(b, x))
+        let mut b = <Self as BoxExt<_>>::new_uninit(flags)?;
+        b.write(x);
+        // SAFETY: We just wrote to it.
+        Ok(unsafe { b.assume_init() })
     }
 
     #[cfg(any(test, testlib))]