diff --git a/websocket-sharp/Net/ChunkStream.cs b/websocket-sharp/Net/ChunkStream.cs
index a019ea8e..0339e2a1 100644
--- a/websocket-sharp/Net/ChunkStream.cs
+++ b/websocket-sharp/Net/ChunkStream.cs
@@ -299,7 +299,10 @@ namespace WebSocketSharp.Net
         _gotIt = false;
       }
 
-      if (_state == InputChunkState.Data && offset < length) {
+      if (_state == InputChunkState.Data) {
+        if (offset >= length)
+          return;
+
         _state = writeData (buffer, ref offset, length);
 
         if (_state == InputChunkState.Data)