diff --git a/xpfe/components/directory/nsDirectoryViewer.cpp b/xpfe/components/directory/nsDirectoryViewer.cpp
index 3b4edd53829..dc0bfdaeb84 100644
--- a/xpfe/components/directory/nsDirectoryViewer.cpp
+++ b/xpfe/components/directory/nsDirectoryViewer.cpp
@@ -115,14 +115,20 @@ static const char               kGopherProtocol[] = "gopher://";
 //
 
 #ifdef MOZ_RDF
-NS_IMPL_THREADSAFE_ISUPPORTS7(nsHTTPIndex,
-                              nsIHTTPIndex,
-                              nsIRDFDataSource,
-                              nsIStreamListener,
-                              nsIDirIndexListener,
-                              nsIRequestObserver,
-                              nsIInterfaceRequestor,
-                              nsIFTPEventSink)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsHTTPIndex)
+    NS_INTERFACE_MAP_ENTRY(nsIHTTPIndex)
+    NS_INTERFACE_MAP_ENTRY(nsIRDFDataSource)
+    NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+    NS_INTERFACE_MAP_ENTRY(nsIDirIndexListener)
+    NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+    NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+    NS_INTERFACE_MAP_ENTRY(nsIFTPEventSink)
+    NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIHTTPIndex)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_1(nsHTTPIndex, mInner)
+NS_IMPL_CYCLE_COLLECTING_ADDREF_AMBIGUOUS(nsHTTPIndex, nsIHttpIndex)
+NS_IMPL_CYCLE_COLLECTING_RELEASE_AMBIGUOUS(nsHTTPIndex, nsIHttpIndex)
 
 NS_IMETHODIMP
 nsHTTPIndex::GetInterface(const nsIID &anIID, void **aResult ) 
diff --git a/xpfe/components/directory/nsDirectoryViewer.h b/xpfe/components/directory/nsDirectoryViewer.h
index ff8f11f3ac8..42c156f5d9e 100644
--- a/xpfe/components/directory/nsDirectoryViewer.h
+++ b/xpfe/components/directory/nsDirectoryViewer.h
@@ -55,6 +55,7 @@
 #include "nsXPIDLString.h"
 #include "nsIDirIndexListener.h"
 #include "nsIFTPChannel.h"
+#include "nsCycleCollectionParticipant.h"
 
 class nsDirectoryViewerFactory : public nsIDocumentLoaderFactory
 {
@@ -145,7 +146,8 @@ public:
     NS_DECL_NSIFTPEVENTSINK
 
     // nsISupports interface
-    NS_DECL_ISUPPORTS
+    NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+    NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsHTTPIndex, nsIHTTPIndex)
 };
 #endif