diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 8ef5b24a9f2..9ce300ce048 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -2506,16 +2506,13 @@ pub type FreevarMap = NodeMap<Vec<Freevar<ast::NodeId>>>;
 
 pub type CaptureModeMap = NodeMap<CaptureClause>;
 
-pub type SmallHirIdVec = SmallVec<[HirId;1]>;
-pub type SmallNodeIdVec = SmallVec<[NodeId;1]>;
-
  // The TraitCandidate's import_ids is empty if the trait is defined in the same module, and
  // has length > 0 if the trait is found through an chain of imports, starting with the
  // import/use statement in the scope where the trait is used.
 #[derive(Clone, Debug)]
 pub struct TraitCandidate {
     pub def_id: DefId,
-    pub import_ids: SmallNodeIdVec,
+    pub import_ids: SmallVec<[NodeId; 1]>,
 }
 
 // Trait method resolution
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index 71721504d5a..635185fe225 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -29,7 +29,7 @@ use rustc::hir::def::{
 };
 use rustc::hir::def::Namespace::*;
 use rustc::hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
-use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap, SmallNodeIdVec};
+use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
 use rustc::ty::{self, DefIdTree};
 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
 use rustc::{bug, span_bug};
@@ -67,6 +67,7 @@ use std::collections::BTreeSet;
 use std::mem::replace;
 use rustc_data_structures::ptr_key::PtrKey;
 use rustc_data_structures::sync::Lrc;
+use smallvec::SmallVec;
 
 use diagnostics::{find_span_of_binding_until_next_binding, extend_span_to_previous_binding};
 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
@@ -4658,10 +4659,9 @@ impl<'a> Resolver<'a> {
         }
     }
 
-    fn find_transitive_imports(&mut self, kind: &NameBindingKind<'_>,
-                               trait_name: &Ident) -> SmallNodeIdVec {
+    fn find_transitive_imports(&mut self, mut kind: &NameBindingKind<'_>,
+                               trait_name: &Ident) -> SmallVec<[NodeId; 1]> {
         let mut import_ids = smallvec![];
-        let mut kind = kind;
         while let NameBindingKind::Import { directive, binding, .. } = *kind {
             self.maybe_unused_trait_imports.insert(directive.id);
             self.add_to_glob_map(&directive, *trait_name);
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
index 148b7d5edb5..314f7e97cd2 100644
--- a/src/librustc_typeck/check/method/probe.rs
+++ b/src/librustc_typeck/check/method/probe.rs
@@ -7,7 +7,6 @@ use crate::check::autoderef::{self, Autoderef};
 use crate::check::FnCtxt;
 use crate::hir::def_id::DefId;
 use crate::hir::def::DefKind;
-use crate::hir::SmallHirIdVec;
 use crate::namespace::Namespace;
 
 use rustc_data_structures::sync::Lrc;
@@ -36,7 +35,7 @@ use std::mem;
 use std::ops::Deref;
 use std::cmp::max;
 
-use smallvec::smallvec;
+use smallvec::{smallvec, SmallVec};
 
 use self::CandidateKind::*;
 pub use self::PickKind::*;
@@ -124,7 +123,7 @@ struct Candidate<'tcx> {
     xform_ret_ty: Option<Ty<'tcx>>,
     item: ty::AssociatedItem,
     kind: CandidateKind<'tcx>,
-    import_ids: SmallHirIdVec,
+    import_ids: SmallVec<[hir::HirId; 1]>,
 }
 
 #[derive(Debug)]
@@ -149,7 +148,7 @@ enum ProbeResult {
 pub struct Pick<'tcx> {
     pub item: ty::AssociatedItem,
     pub kind: PickKind<'tcx>,
-    pub import_ids: hir::SmallHirIdVec,
+    pub import_ids: SmallVec<[hir::HirId; 1]>,
 
     // Indicates that the source expression should be autoderef'd N times
     //
@@ -894,7 +893,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
     }
 
     fn assemble_extension_candidates_for_trait(&mut self,
-                                               import_ids: SmallHirIdVec,
+                                               import_ids: SmallVec<[hir::HirId; 1]>,
                                                trait_def_id: DefId)
                                                -> Result<(), MethodError<'tcx>> {
         debug!("assemble_extension_candidates_for_trait(trait_def_id={:?})",