diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests/MTConnectSampleLagTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests/MTConnectSampleLagTests.cs
index 517a95de..15b4dbfc 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests/MTConnectSampleLagTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.MTConnect.Tests/MTConnectSampleLagTests.cs
@@ -130,8 +130,11 @@ public sealed class MTConnectSampleLagTests
         try
         {
             // The NEXT enumeration (the raised one) is refused the way a real Agent refuses a count above its buffer.
+            // Enqueued only once the first stream has consumed a chunk — i.e. is past its own one-shot-failure check —
+            // so the failure can only ever hit the raised stream (enqueueing earlier raced the first enumeration).
+            await client.PumpAsync(Chunk(Primed, 2, last: 900)).WaitAsync(Watchdog, Ct);
             client.SampleFailures.Enqueue(new InvalidDataException("MTConnectError: INVALID_REQUEST count too large"));
-            for (var i = 0; i < 3; i++)
+            for (var i = 1; i < 3; i++)
                 await client.PumpAsync(Chunk(Primed + (2 * i), 2, last: 900)).WaitAsync(Watchdog, Ct);
 
             await client.WaitForSampleCallsAsync(3).WaitAsync(Watchdog, Ct);