diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index c79e25f4781..8683e954019 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -890,7 +890,7 @@ impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
 ///
 /// Trait references also appear in object types like `Foo<U>`, but in
 /// that case the `Self` parameter is absent from the substitutions.
-#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
 #[derive(HashStable, TypeFoldable)]
 pub struct TraitRef<'tcx> {
     pub def_id: DefId,