diff --git a/src/librustc/mir/interpret/allocation.rs b/src/librustc/mir/interpret/allocation.rs
index e55997099c82b..cc92b63256c1f 100644
--- a/src/librustc/mir/interpret/allocation.rs
+++ b/src/librustc/mir/interpret/allocation.rs
@@ -65,6 +65,17 @@ pub trait AllocationExtra<Tag>: ::std::fmt::Debug + Default + Clone {
     ) -> EvalResult<'tcx> {
         Ok(())
     }
+
+    /// Hook for performing extra checks on a memory deallocation.
+    /// `size` will be the size of the allocation.
+    #[inline]
+    fn memory_deallocated(
+        _alloc: &mut Allocation<Tag, Self>,
+        _ptr: Pointer<Tag>,
+        _size: Size,
+    ) -> EvalResult<'tcx> {
+        Ok(())
+    }
 }
 
 impl AllocationExtra<()> for () {}
diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index 047996777ea96..1efd7ca7f8973 100644
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -17,7 +17,7 @@ use std::hash::Hash;
 
 use rustc::hir::{self, def_id::DefId};
 use rustc::mir;
-use rustc::ty::{self, layout::{Size, TyLayout}, query::TyCtxtAt};
+use rustc::ty::{self, layout::TyLayout, query::TyCtxtAt};
 
 use super::{
     Allocation, AllocId, EvalResult, Scalar, AllocationExtra,
@@ -174,16 +174,6 @@ pub trait Machine<'a, 'mir, 'tcx>: Sized {
         dest: PlaceTy<'tcx, Self::PointerTag>,
     ) -> EvalResult<'tcx>;
 
-    /// Hook for performing extra checks when memory gets deallocated.
-    #[inline]
-    fn memory_deallocated(
-        _alloc: &mut Allocation<Self::PointerTag, Self::AllocExtra>,
-        _ptr: Pointer<Self::PointerTag>,
-        _size: Size,
-    ) -> EvalResult<'tcx> {
-        Ok(())
-    }
-
     /// Add the tag for a newly allocated pointer.
     fn tag_new_allocation(
         ecx: &mut EvalContext<'a, 'mir, 'tcx, Self>,
diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index 10bc984a447a3..e125927e7d273 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -225,7 +225,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
 
         // Let the machine take some extra action
         let size = Size::from_bytes(alloc.bytes.len() as u64);
-        M::memory_deallocated(&mut alloc, ptr, size)?;
+        AllocationExtra::memory_deallocated(&mut alloc, ptr, size)?;
 
         // Don't forget to remember size and align of this now-dead allocation
         let old = self.dead_alloc_map.insert(