diff --git a/xpcom/ds/nsArray.cpp b/xpcom/ds/nsArray.cpp
index 91cbb21a165..2eeb0054804 100644
--- a/xpcom/ds/nsArray.cpp
+++ b/xpcom/ds/nsArray.cpp
@@ -54,7 +54,18 @@ nsArray::~nsArray()
 {
     Clear();
 }
-    
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsArray)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsArray)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(nsArray)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsArray)
+    tmp->Clear();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsArray)
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mArray)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
 NS_IMETHODIMP
 nsArray::GetLength(PRUint32* aLength)
 {
diff --git a/xpcom/ds/nsArray.h b/xpcom/ds/nsArray.h
index 7b74dd540b8..7f59888eb70 100644
--- a/xpcom/ds/nsArray.h
+++ b/xpcom/ds/nsArray.h
@@ -42,6 +42,7 @@
 #include "nsIMutableArray.h"
 #include "nsCOMArray.h"
 #include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
 
 #define NS_ARRAY_CLASSNAME \
   "nsIArray implementation"
@@ -63,7 +64,8 @@ public:
     nsArray(const nsCOMArray_base& aBaseArray) : mArray(aBaseArray)
     { }
     
-    NS_DECL_ISUPPORTS
+    NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+    NS_DECL_CYCLE_COLLECTION_CLASS(nsArray)
     NS_DECL_NSIARRAY
     NS_DECL_NSIMUTABLEARRAY
 
diff --git a/xpcom/ds/xpcomds.gqi b/xpcom/ds/xpcomds.gqi
index a41d0e9d786..cc07f811904 100644
--- a/xpcom/ds/xpcomds.gqi
+++ b/xpcom/ds/xpcomds.gqi
@@ -34,7 +34,11 @@
 %pseudo-iid nsIByteBuffer e4a6e4b0-93b4-11d1-895b-006008911b81
 %pseudo-iid nsIUnicharBuffer 14cf6970-93b5-11d1-895b-006008911b81
 
-NS_IMPL_ISUPPORTS2(nsArray, nsIArray, nsIMutableArray)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsArray)
+  NS_INTERFACE_MAP_ENTRY(nsIArray)
+  NS_INTERFACE_MAP_ENTRY(nsIMutableArray)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIMutableArray)
+NS_INTERFACE_MAP_END
 
 NS_IMPL_ISUPPORTS1(nsSimpleProperty, nsIProperty)