diff --git a/websocket-sharp/Net/HttpUtility.cs b/websocket-sharp/Net/HttpUtility.cs
index 6cadb748..24d7f0f2 100644
--- a/websocket-sharp/Net/HttpUtility.cs
+++ b/websocket-sharp/Net/HttpUtility.cs
@@ -518,6 +518,17 @@ namespace WebSocketSharp.Net
              || c == '~';
     }
 
+    private static void urlDecode (byte[] bytes, int offset, Stream output)
+    {
+      var num = getNumber (bytes, offset + 1, 2);
+      if (num == -1) {
+        output.Write (bytes, offset, 3);
+        return;
+      }
+
+      output.WriteByte ((byte) num);
+    }
+
     private static void urlEncode (byte b, Stream output)
     {
       if (b > 31 && b < 127) {