diff --git a/dom/base/Timeout.cpp b/dom/base/Timeout.cpp
index 1269f75494..3eaa57a11c 100644
--- a/dom/base/Timeout.cpp
+++ b/dom/base/Timeout.cpp
@@ -40,12 +40,14 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(Timeout)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(Timeout)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mWindow)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mTimer)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mPrincipal)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mScriptHandler)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(Timeout)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWindow)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mTimer)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPrincipal)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mScriptHandler)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END