diff --git a/packages/cultmesh-py/tests/test_cultmesh.py b/packages/cultmesh-py/tests/test_cultmesh.py
index 819dfc01..cccb2ecb 100644
--- a/packages/cultmesh-py/tests/test_cultmesh.py
+++ b/packages/cultmesh-py/tests/test_cultmesh.py
@@ -4536,7 +4536,7 @@ class CultMeshRudpSendFailureTests(unittest.TestCase):
                     raise OSError("injected send failure")
                 return original_sendto(sock, data, *args)
 
-            request = msgpack.packb(hello(runtime_id="probe"), use_bin_type=True)
+            request = hello(runtime_id="probe").to_bytes()
             with patch.object(socket.socket, "sendto", sendto):
                 # The server's reply and ack to X both fail to send.
                 x.send("schema", request)
diff --git a/tests/GameCult.Networking.Tests/CultNetRudpSendFailureTests.cs b/tests/GameCult.Networking.Tests/CultNetRudpSendFailureTests.cs
index 162ad4c6..359b842f 100644
--- a/tests/GameCult.Networking.Tests/CultNetRudpSendFailureTests.cs
+++ b/tests/GameCult.Networking.Tests/CultNetRudpSendFailureTests.cs
@@ -1,4 +1,5 @@
 #nullable enable
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Net;