diff --git a/src/harness/loggedIO.ts b/src/harness/loggedIO.ts
index 3adb04adf4b..a2d9ff1f00e 100644
--- a/src/harness/loggedIO.ts
+++ b/src/harness/loggedIO.ts
@@ -95,6 +95,7 @@ module Playback {
 
     function createEmptyLog(): IOLog {
         return {
+            timestamp: (new Date()).toString(),
             arguments: [],
             currentDirectory: '',
             filesRead: [],