diff --git a/src/librustc_hir/definitions.rs b/src/librustc_hir/definitions.rs
index 679fd1668dd..9913f92d2d9 100644
--- a/src/librustc_hir/definitions.rs
+++ b/src/librustc_hir/definitions.rs
@@ -337,11 +337,6 @@ impl Definitions {
         self.local_def_id_to_hir_id(def_id)
     }
 
-    #[inline]
-    pub fn hir_id_to_node_id(&self, hir_id: hir::HirId) -> ast::NodeId {
-        self.hir_id_to_node_id[&hir_id]
-    }
-
     #[inline]
     pub fn local_def_id_to_hir_id(&self, id: LocalDefId) -> hir::HirId {
         let node_id = self.def_id_to_node_id[id];
@@ -356,7 +351,7 @@ impl Definitions {
 
     #[inline]
     pub fn opt_hir_id_to_local_def_id(&self, hir_id: hir::HirId) -> Option<LocalDefId> {
-        let node_id = self.hir_id_to_node_id(hir_id);
+        let node_id = self.hir_id_to_node_id[&hir_id];
         self.opt_local_def_id(node_id)
     }
 
diff --git a/src/librustc_middle/hir/map/collector.rs b/src/librustc_middle/hir/map/collector.rs
index ae169976698..dce06a5f7ee 100644
--- a/src/librustc_middle/hir/map/collector.rs
+++ b/src/librustc_middle/hir/map/collector.rs
@@ -242,10 +242,8 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
         // Make sure that the DepNode of some node coincides with the HirId
         // owner of that node.
         if cfg!(debug_assertions) {
-            let node_id = self.definitions.hir_id_to_node_id(hir_id);
-
             if hir_id.owner != self.current_dep_node_owner {
-                let node_str = match self.definitions.opt_local_def_id(node_id) {
+                let node_str = match self.definitions.opt_hir_id_to_local_def_id(hir_id) {
                     Some(def_id) => self.definitions.def_path(def_id).to_string_no_crate(),
                     None => format!("{:?}", node),
                 };
@@ -335,9 +333,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         debug!("visit_item: {:?}", i);
         debug_assert_eq!(
             i.hir_id.owner,
-            self.definitions
-                .opt_local_def_id(self.definitions.hir_id_to_node_id(i.hir_id))
-                .unwrap()
+            self.definitions.opt_hir_id_to_local_def_id(i.hir_id).unwrap()
         );
         self.with_dep_node_owner(i.hir_id.owner, i, |this, hash| {
             this.insert_with_hash(i.span, i.hir_id, Node::Item(i), hash);
@@ -369,9 +365,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     fn visit_trait_item(&mut self, ti: &'hir TraitItem<'hir>) {
         debug_assert_eq!(
             ti.hir_id.owner,
-            self.definitions
-                .opt_local_def_id(self.definitions.hir_id_to_node_id(ti.hir_id))
-                .unwrap()
+            self.definitions.opt_hir_id_to_local_def_id(ti.hir_id).unwrap()
         );
         self.with_dep_node_owner(ti.hir_id.owner, ti, |this, hash| {
             this.insert_with_hash(ti.span, ti.hir_id, Node::TraitItem(ti), hash);
@@ -385,9 +379,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     fn visit_impl_item(&mut self, ii: &'hir ImplItem<'hir>) {
         debug_assert_eq!(
             ii.hir_id.owner,
-            self.definitions
-                .opt_local_def_id(self.definitions.hir_id_to_node_id(ii.hir_id))
-                .unwrap()
+            self.definitions.opt_hir_id_to_local_def_id(ii.hir_id).unwrap()
         );
         self.with_dep_node_owner(ii.hir_id.owner, ii, |this, hash| {
             this.insert_with_hash(ii.span, ii.hir_id, Node::ImplItem(ii), hash);