diff --git a/src/librustc_plugin/build.rs b/src/librustc_plugin/build.rs
index b8c114f5bd3..75046f6aeb8 100644
--- a/src/librustc_plugin/build.rs
+++ b/src/librustc_plugin/build.rs
@@ -35,8 +35,6 @@ impl<'v> ItemLikeVisitor<'v> for RegistrarFinder {
 
     fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
     }
-
-    fn visit_expr_id(&mut self, _: hir::ExprId) { }
 }
 
 /// Find the function marked with `#[plugin_registrar]`, if any.