diff --git a/src/librustc/arena.rs b/src/librustc/arena.rs
index 1f1060ee243f..a4c3326c848b 100644
--- a/src/librustc/arena.rs
+++ b/src/librustc/arena.rs
@@ -24,18 +24,9 @@ macro_rules! declare_arena {
     }
 }
 
-macro_rules! impl_specialized_decodable {
-    ([decode] $ty:ty, $tcx:lifetime) => {
-        impl<$tcx> serialize::UseSpecializedDecodable for &$tcx $ty {}
-    };
-    ([] $ty:ty, $tcx:lifetime) => {};
-}
-
 macro_rules! impl_arena_allocatable {
     ([], [$($a:tt $name:ident: $ty:ty,)*], $tcx:lifetime) => {
         $(
-            impl_specialized_decodable!($a $ty, $tcx);
-
             impl ArenaAllocatable for $ty {}
             impl<$tcx> ArenaField<$tcx> for $ty {
                 #[inline]
diff --git a/src/libserialize/serialize.rs b/src/libserialize/serialize.rs
index 234435f40a06..8e1229f9c43c 100644
--- a/src/libserialize/serialize.rs
+++ b/src/libserialize/serialize.rs
@@ -911,4 +911,5 @@ impl<T: UseSpecializedDecodable> Decodable for T {
 impl<'a, T: ?Sized + Encodable> UseSpecializedEncodable for &'a T {}
 impl<T: ?Sized + Encodable> UseSpecializedEncodable for Box<T> {}
 impl<T: Decodable> UseSpecializedDecodable for Box<T> {}
+impl<'a, T: ?Sized + Decodable> UseSpecializedDecodable for &'a T {}
 impl<'a, T: ?Sized + Decodable> UseSpecializedDecodable for &'a [T] {}