diff --git a/src/librustc/hir/map/def_collector.rs b/src/librustc/hir/map/def_collector.rs
index ea1f8aac7a55..b0a717e18f98 100644
--- a/src/librustc/hir/map/def_collector.rs
+++ b/src/librustc/hir/map/def_collector.rs
@@ -30,19 +30,12 @@ pub struct DefCollector<'ast> {
 }
 
 impl<'ast> DefCollector<'ast> {
-    pub fn root(definitions: &'ast mut Definitions) -> DefCollector<'ast> {
-        let mut collector = DefCollector {
+    pub fn new(definitions: &'ast mut Definitions) -> DefCollector<'ast> {
+        DefCollector {
             hir_crate: None,
             definitions: definitions,
             parent_def: None,
-        };
-        let root = collector.create_def_with_parent(None, CRATE_NODE_ID, DefPathData::CrateRoot);
-        assert_eq!(root, CRATE_DEF_INDEX);
-        collector.parent_def = Some(root);
-
-        collector.create_def_with_parent(Some(CRATE_DEF_INDEX), DUMMY_NODE_ID, DefPathData::Misc);
-
-        collector
+        }
     }
 
     pub fn extend(parent_node: NodeId,
@@ -50,11 +43,7 @@ impl<'ast> DefCollector<'ast> {
                   parent_def_id: DefId,
                   definitions: &'ast mut Definitions)
                   -> DefCollector<'ast> {
-        let mut collector = DefCollector {
-            hir_crate: None,
-            parent_def: None,
-            definitions: definitions,
-        };
+        let mut collector = DefCollector::new(definitions);
 
         assert_eq!(parent_def_path.krate, parent_def_id.krate);
         let root_path = Box::new(InlinedRootPath {
@@ -68,17 +57,21 @@ impl<'ast> DefCollector<'ast> {
         collector
     }
 
+    pub fn collect_root(&mut self) {
+        let root = self.create_def_with_parent(None, CRATE_NODE_ID, DefPathData::CrateRoot);
+        assert_eq!(root, CRATE_DEF_INDEX);
+        self.parent_def = Some(root);
+
+        self.create_def_with_parent(Some(CRATE_DEF_INDEX), DUMMY_NODE_ID, DefPathData::Misc);
+    }
+
     pub fn walk_item(&mut self, ii: &'ast InlinedItem, krate: &'ast hir::Crate) {
         self.hir_crate = Some(krate);
         ii.visit(self);
     }
 
-    fn parent_def(&self) -> Option<DefIndex> {
-        self.parent_def
-    }
-
     fn create_def(&mut self, node_id: NodeId, data: DefPathData) -> DefIndex {
-        let parent_def = self.parent_def();
+        let parent_def = self.parent_def;
         debug!("create_def(node_id={:?}, data={:?}, parent_def={:?})", node_id, data, parent_def);
         self.definitions.create_def_with_parent(parent_def, node_id, data)
     }
diff --git a/src/librustc/hir/map/definitions.rs b/src/librustc/hir/map/definitions.rs
index f404f60cc9ce..5cfb71f4fc87 100644
--- a/src/librustc/hir/map/definitions.rs
+++ b/src/librustc/hir/map/definitions.rs
@@ -225,7 +225,8 @@ impl Definitions {
     }
 
     pub fn collect(&mut self, krate: &ast::Crate) {
-        let mut def_collector = DefCollector::root(self);
+        let mut def_collector = DefCollector::new(self);
+        def_collector.collect_root();
         visit::walk_crate(&mut def_collector, krate);
     }