diff --git a/tests/ClaudeDo.Worker.Tests/External/ExternalMcpServiceTests.cs b/tests/ClaudeDo.Worker.Tests/External/ExternalMcpServiceTests.cs
index 33fe127d..4bb9bead 100644
--- a/tests/ClaudeDo.Worker.Tests/External/ExternalMcpServiceTests.cs
+++ b/tests/ClaudeDo.Worker.Tests/External/ExternalMcpServiceTests.cs
@@ -2197,7 +2197,7 @@ public sealed class ExternalMcpServiceTests : IDisposable
         }
 
         var sut = BuildSut(CreateQueue());
-        var result = await sut.PreviewMergeSet([subsetTask.Id, supersetTask.Id], "main", CancellationToken.None);
+        var result = await sut.PreviewMergeSet([subsetTask.Id, supersetTask.Id], "main", cancellationToken: CancellationToken.None);
 
         var relation = Assert.Single(result.Subsets);
         Assert.Equal(subsetTask.Id, relation.TaskId);