diff --git a/mozilla/content/base/src/nsContentList.cpp b/mozilla/content/base/src/nsContentList.cpp
index 451eac25f24..1cf22a14ea2 100644
--- a/mozilla/content/base/src/nsContentList.cpp
+++ b/mozilla/content/base/src/nsContentList.cpp
@@ -400,6 +400,7 @@ nsContentList::~nsContentList()
 // QueryInterface implementation for nsContentList
 NS_INTERFACE_MAP_BEGIN(nsContentList)
   NS_INTERFACE_MAP_ENTRY(nsIDOMHTMLCollection)
+  NS_INTERFACE_MAP_ENTRY(nsIDocumentObserver)
   NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(ContentList)
 NS_INTERFACE_MAP_END_INHERITING(nsBaseContentList)
 
diff --git a/mozilla/content/xul/templates/src/nsXULTemplateBuilder.cpp b/mozilla/content/xul/templates/src/nsXULTemplateBuilder.cpp
index e118a9f883e..f557addff24 100644
--- a/mozilla/content/xul/templates/src/nsXULTemplateBuilder.cpp
+++ b/mozilla/content/xul/templates/src/nsXULTemplateBuilder.cpp
@@ -236,6 +236,7 @@ NS_IMPL_RELEASE(nsXULTemplateBuilder)
 
 NS_INTERFACE_MAP_BEGIN(nsXULTemplateBuilder)
   NS_INTERFACE_MAP_ENTRY(nsIXULTemplateBuilder)
+  NS_INTERFACE_MAP_ENTRY(nsIDocumentObserver)
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIXULTemplateBuilder)
   NS_INTERFACE_MAP_ENTRY_DOM_CLASSINFO(XULTemplateBuilder)
 NS_INTERFACE_MAP_END