--- a/xpcom/glue/nsTArray.h
+++ b/xpcom/glue/nsTArray.h
@@ -1516,16 +1516,22 @@ public:
   // @param aArray    The elements to append to this array.
   // @param aArrayLen The number of elements to append to this array.
   // @return          A pointer to the new elements in the array, or null if
   //                  the operation failed due to insufficient memory.
 protected:
   template<class Item, typename ActualAlloc = Alloc>
   elem_type* AppendElements(const Item* aArray, size_type aArrayLen);
 
+  template<class Item, size_t Length, typename ActualAlloc = Alloc>
+  elem_type* AppendElements(const mozilla::Array<Item, Length>& aArray)
+  {
+    return AppendElements<Item, ActualAlloc>(&aArray[0], Length);
+  }
+
 public:
 
   template<class Item>
   /* MOZ_MUST_USE */
   elem_type* AppendElements(const Item* aArray, size_type aArrayLen,
                             const mozilla::fallible_t&)
   {
     return AppendElements<Item, FallibleAlloc>(aArray, aArrayLen);