diff --git a/src/mscorlib/ref/mscorlib.cs b/src/mscorlib/ref/mscorlib.cs
index 965e727ee913..ef85f3caf5c3 100644
--- a/src/mscorlib/ref/mscorlib.cs
+++ b/src/mscorlib/ref/mscorlib.cs
@@ -4227,6 +4227,7 @@ public void AddRange(System.Collections.Generic.IEnumerable<T> collection) { }
         public int BinarySearch(int index, int count, T item, System.Collections.Generic.IComparer<T> comparer) { return default(int); }
         public void Clear() { }
         public bool Contains(T item) { return default(bool); }
+        public List<TOutput> ConvertAll<TOutput>(System.Converter<T,TOutput> converter) { throw null; }
         public void CopyTo(T[] array) { }
         public void CopyTo(T[] array, int arrayIndex) { }
         public void CopyTo(int index, T[] array, int arrayIndex, int count) { }