diff --git a/lib/csharp/src/Collections/THashSet.cs b/lib/csharp/src/Collections/THashSet.cs
index cd4e19b..a995769 100644
--- a/lib/csharp/src/Collections/THashSet.cs
+++ b/lib/csharp/src/Collections/THashSet.cs
@@ -37,7 +37,7 @@
 
 		public bool IsReadOnly
 		{
-			get { return set.IsReadOnly; }
+			get { return false; }
 		}
 
 		public void Add(T item)