diff --git a/Implab/Diagnostics/TextFileListener.cs b/Implab/Diagnostics/TextFileListener.cs
--- a/Implab/Diagnostics/TextFileListener.cs
+++ b/Implab/Diagnostics/TextFileListener.cs
@@ -19,7 +19,7 @@ namespace Implab.Diagnostics {
             var msg = new StringBuilder();
             for (int i = 0; i < args.Operation.Level; i++)
                 msg.Append("  ");
-            msg.AppendFormat("[{0}]:{1}: {2}", args.ThreadId, args.Channel, entry);
+            msg.AppendFormat("[{0}]+{3}ms:{1}: {2}", args.ThreadId, args.Channel, entry, args.OperationTimeOffset);
 
             lock (m_lock) {
                 if (!IsDisposed) {