diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/RetentionTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/RetentionTests.cs
index 50870b4a..35309fdb 100644
--- a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/RetentionTests.cs
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/RetentionTests.cs
@@ -195,16 +195,33 @@ public sealed class RetentionTests(SqlHistorianFixture fx)
             cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Sample WITH (TABLOCKX, HOLDLOCK)";
             await cmd.ExecuteScalarAsync();
         }
+        short holderSpid;
+        await using (var cmd = holder.CreateCommand())
+        {
+            cmd.Transaction = tx;
+            cmd.CommandText = "SELECT CAST(@@SPID AS smallint)";
+            holderSpid = (short)(await cmd.ExecuteScalarAsync())!;
+        }
 
         using var cts = new CancellationTokenSource();
         var purger = new SqlServerHistorianRetention(c, b, TimeSpan.FromHours(1), 30, 4000, time: new FixedTime(Now));
         var purge = purger.PurgeAsync(cts.Token);
-        await Task.Delay(500);
-        purge.IsCompleted.ShouldBeFalse("the DELETE must be blocked behind the holder's table lock");
+
+        // Cancel only once the server reports a DELETE actually blocked behind the holder — a fixed delay could
+        // cancel during bootstrap/applock acquisition on a slow host and never exercise the mid-command path.
+        var deadline = DateTime.UtcNow.AddSeconds(15);
+        while (await CountAsync(
+                   $"SELECT COUNT(*) FROM sys.dm_exec_requests WHERE blocking_session_id = {holderSpid} AND command = 'DELETE'") == 0)
+        {
+            purge.IsCompleted.ShouldBeFalse("the purge finished without ever blocking on the holder's table lock");
+            DateTime.UtcNow.ShouldBeLessThan(deadline, "the purge's DELETE never blocked behind the holder");
+            await Task.Delay(50);
+        }
         cts.Cancel();
 
-        // SqlClient may surface the attention as a SqlException rather than OperationCanceledException.
-        await Should.ThrowAsync<Exception>(() => purge);
+        // SqlClient surfaces the attention as OperationCanceledException or as a SqlException.
+        var ex = await Should.ThrowAsync<Exception>(() => purge);
+        (ex is OperationCanceledException or SqlException).ShouldBeTrue($"unexpected {ex.GetType().Name}: {ex.Message}");
 
         await tx.RollbackAsync();
         (await LockIsFreeAsync(s)).ShouldBeTrue();