diff --git a/samples/EverythingServer/SubscriptionMessageSender.cs b/samples/EverythingServer/SubscriptionMessageSender.cs
index 774d9852..290d6a67 100644
--- a/samples/EverythingServer/SubscriptionMessageSender.cs
+++ b/samples/EverythingServer/SubscriptionMessageSender.cs
@@ -2,6 +2,8 @@
 using ModelContextProtocol;
 using ModelContextProtocol.Server;
 
+namespace EverythingServer;
+
 internal class SubscriptionMessageSender(IMcpServer server, HashSet<string> subscriptions) : BackgroundService
 {
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
diff --git a/src/ModelContextProtocol/Protocol/Messages/ProgressToken.cs b/src/ModelContextProtocol/Protocol/Messages/ProgressToken.cs
index ac5ceb18..0e58a9cb 100644
--- a/src/ModelContextProtocol/Protocol/Messages/ProgressToken.cs
+++ b/src/ModelContextProtocol/Protocol/Messages/ProgressToken.cs
@@ -39,7 +39,7 @@ public ProgressToken(long value)
     public override string? ToString() =>
         _token is string stringValue ? stringValue :
         _token is long longValue ? longValue.ToString(CultureInfo.InvariantCulture) :
-        null;
+        string.Empty;
 
     /// <inheritdoc />
     public bool Equals(ProgressToken other) => Equals(_token, other._token);