diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0292123..bc2e054 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 * Update signature for implementations of `Iterable.singleWhere` to include 
   optional argument.
-   
+
 ## 0.13.2+1
 
 * Changed the implementation of `Set` and `List` classes to use base classes
diff --git a/lib/dom.dart b/lib/dom.dart
index df9655e..8a8f74d 100644
--- a/lib/dom.dart
+++ b/lib/dom.dart
@@ -969,11 +969,11 @@
       _filtered.getRange(start, end);
   // TODO(sigmund): this should be typed Element, but we currently run into a
   // bug where ListMixin<E>.indexOf() expects Object as the argument.
-  int indexOf(element, [int start = 0]) => _filtered.indexOf(element, start);
+  int indexOf(Object element, [int start = 0]) => _filtered.indexOf(element, start);
 
   // TODO(sigmund): this should be typed Element, but we currently run into a
   // bug where ListMixin<E>.lastIndexOf() expects Object as the argument.
-  int lastIndexOf(element, [int start]) {
+  int lastIndexOf(Object element, [int start]) {
     if (start == null) start = length - 1;
     return _filtered.lastIndexOf(element, start);
   }