diff --git a/src/librustc_trans/collector.rs b/src/librustc_trans/collector.rs
index 5c7b004375e..a4439b0796e 100644
--- a/src/librustc_trans/collector.rs
+++ b/src/librustc_trans/collector.rs
@@ -1124,6 +1124,8 @@ impl<'b, 'a, 'v> ItemLikeVisitor<'v> for RootCollector<'b, 'a, 'v> {
             _ => { /* Nothing to do here */ }
         }
     }
+
+    fn visit_expr_id(&mut self, _: hir::ExprId) { }
 }
 
 fn create_trans_items_for_default_impls<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>,
diff --git a/src/librustc_trans/symbol_names_test.rs b/src/librustc_trans/symbol_names_test.rs
index aa23a181722..de6a13ec80b 100644
--- a/src/librustc_trans/symbol_names_test.rs
+++ b/src/librustc_trans/symbol_names_test.rs
@@ -81,5 +81,7 @@ impl<'a, 'tcx> Visitor<'tcx> for SymbolNamesTest<'a, 'tcx> {
         self.process_attrs(ii.id);
         intravisit::walk_impl_item(self, ii)
     }
+
+    fn visit_expr_id(&mut self, _: hir::ExprId) { }
 }