diff --git a/websocket-sharp/WebSocketFrame.cs b/websocket-sharp/WebSocketFrame.cs
index 2d8b5953..0c02b8d1 100644
--- a/websocket-sharp/WebSocketFrame.cs
+++ b/websocket-sharp/WebSocketFrame.cs
@@ -139,6 +139,16 @@ namespace WebSocketSharp
       }
     }
 
+    internal ulong FullPayloadLength {
+      get {
+        return _payloadLength < 126
+               ? _payloadLength
+               : _payloadLength == 126
+                 ? _extPayloadLength.ToUInt16 (ByteOrder.Big)
+                 : _extPayloadLength.ToUInt64 (ByteOrder.Big);
+      }
+    }
+
     #endregion
 
     #region Public Properties
@@ -155,16 +165,6 @@ namespace WebSocketSharp
       }
     }
 
-    public ulong FullPayloadLength {
-      get {
-        return _payloadLength < 126
-               ? _payloadLength
-               : _payloadLength == 126
-                 ? _extPayloadLength.ToUInt16 (ByteOrder.Big)
-                 : _extPayloadLength.ToUInt64 (ByteOrder.Big);
-      }
-    }
-
     public bool IsBinary {
       get {
         return _opcode == Opcode.Binary;