diff --git a/src/librustc/hir/def_id.rs b/src/librustc/hir/def_id.rs
index 47604b961ae..ce2baa73897 100644
--- a/src/librustc/hir/def_id.rs
+++ b/src/librustc/hir/def_id.rs
@@ -187,6 +187,7 @@ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 
 
 impl DefId {
+    /// Make a local `DefId` with the given index.
     pub fn local(index: DefIndex) -> DefId {
         DefId { krate: LOCAL_CRATE, index: index }
     }