diff --git a/source/Halibut.Tests/Support/LatestClientAndLatestServiceBuilder.cs b/source/Halibut.Tests/Support/LatestClientAndLatestServiceBuilder.cs
index b1d37fd0d..b9f043b71 100644
--- a/source/Halibut.Tests/Support/LatestClientAndLatestServiceBuilder.cs
+++ b/source/Halibut.Tests/Support/LatestClientAndLatestServiceBuilder.cs
@@ -297,6 +297,12 @@ public LatestClientAndLatestServiceBuilder WithClientTrustingTheWrongCertificate
             return this;
         }
 
+        public LatestClientAndLatestServiceBuilder WithClientTrustingNoThumbprints()
+        {
+            clientBuilder.WithClientTrustingNoThumbprints();
+            return this;
+        }
+
         public LatestClientAndLatestServiceBuilder WithServiceTrustingTheWrongCertificate()
         {
             serviceBuilder.WithServiceTrustingTheWrongCertificate();
diff --git a/source/Halibut.Tests/Support/LatestClientBuilder.cs b/source/Halibut.Tests/Support/LatestClientBuilder.cs
index eff387b75..1de31111f 100644
--- a/source/Halibut.Tests/Support/LatestClientBuilder.cs
+++ b/source/Halibut.Tests/Support/LatestClientBuilder.cs
@@ -24,7 +24,8 @@ public class LatestClientBuilder : IClientBuilder
         CertAndThumbprint clientCertAndThumbprint;
         readonly PollingQueueTestCase? pollingQueueTestCase;
 
-        string clientTrustsThumbprint; 
+        string clientTrustsThumbprint;
+        bool clientTrustsNoThumbprints;
         IRpcObserver? clientRpcObserver;
         Func<int, PortForwarder>? portForwarderFactory;
         Reference<PortForwarder>? portForwarderReference;
@@ -181,6 +182,12 @@ public LatestClientBuilder WithClientTrustingTheWrongCertificate()
             clientTrustsThumbprint = CertAndThumbprint.Wrong.Thumbprint;
             return this;
         }
+
+        public LatestClientBuilder WithClientTrustingNoThumbprints()
+        {
+            clientTrustsNoThumbprints = true;
+            return this;
+        }
         
         public LatestClientBuilder WithClientRpcObserver(IRpcObserver? clientRpcObserver)
         {
@@ -215,7 +222,10 @@ public async Task<LatestClient> Build(CancellationToken cancellationToken)
             }
 
             var client = clientBuilder.Build();
-            client.Trust(clientTrustsThumbprint);
+            if (!clientTrustsNoThumbprints)
+            {
+                client.Trust(clientTrustsThumbprint);
+            }
             
             var disposableCollection = new DisposableCollection();
             PortForwarder? portForwarder = null;
diff --git a/source/Halibut.Tests/Transport/Observability/ConnectionObserverFixture.cs b/source/Halibut.Tests/Transport/Observability/ConnectionObserverFixture.cs
index 426c342a4..65fd17164 100644
--- a/source/Halibut.Tests/Transport/Observability/ConnectionObserverFixture.cs
+++ b/source/Halibut.Tests/Transport/Observability/ConnectionObserverFixture.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
@@ -83,10 +82,10 @@ public async Task ObserveUnauthorizedPollingConnections(ClientAndServiceTestCase
             await using (var clientAndBuilder = await clientAndServiceTestCase.CreateTestCaseBuilder()
                              .WithStandardServices()
                              .AsLatestClientAndLatestServiceBuilder()
+                             .WithClientTrustingNoThumbprints()
                              .WithConnectionObserverOnTcpServer(connectionsObserver)
                              .Build(CancellationToken))
             {
-                clientAndBuilder.Client.TrustOnly(new List<string>());
 
                 using var cts = new CancellationTokenSource();
                 var token = cts.Token;