timotei

diff --git a/src/MonoTorrent/MonoTorrent.Client/Tracker/HTTPTracker.cs b/src/MonoTorrent/MonoTorrent.Client/Tracker/HTTPTracker.cs
index 413e043..e8775e7 100644
--- a/src/MonoTorrent/MonoTorrent.Client/Tracker/HTTPTracker.cs
+++ b/src/MonoTorrent/MonoTorrent.Client/Tracker/HTTPTracker.cs
@@ -76,7 +76,7 @@ namespace MonoTorrent.Client.Tracker
             byte[] passwordKey = new byte[8];
             lock (random)
                 random.NextBytes(passwordKey);
-            Key = HttpUtility.UrlEncode(passwordKey);
+            Key = UriHelper.UrlEncode(passwordKey);
         }

         public override void Announce(AnnounceParameters parameters, object state)
diff --git a/src/MonoTorrent/MonoTorrent.Tracker/Frontend/AnnounceParameters.cs b/src/MonoTorrent/MonoTorrent.Tracker/Frontend/AnnounceParameters.cs
index e49d1d9..e31e97b 100644
--- a/src/MonoTorrent/MonoTorrent.Tracker/Frontend/AnnounceParameters.cs
+++ b/src/MonoTorrent/MonoTorrent.Tracker/Frontend/AnnounceParameters.cs
@@ -163,7 +163,7 @@ namespace MonoTorrent.Tracker
                 Response.Add(FailureKey, (BEncodedString)("mandatory announce parameter " + field + " in query missing"));
                 return;
             }
-            byte[] hash = HttpUtility.UrlDecodeToBytes(Parameters["info_hash"]);
+            byte[] hash = UriHelper.UrlDecode(Parameters["info_hash"]);
             if (hash.Length != 20)
             {
                 Response.Add(FailureKey, (BEncodedString)(string.Format("infohash was {0} bytes long, it must be 20 bytes long.", hash.Length)));