diff --git a/Control/AthenaConfiguration/python/AllConfigFlags.py b/Control/AthenaConfiguration/python/AllConfigFlags.py
index 4d641fabca3152645b60c59d89cb198bab07f4ac..d60f1a1e36229ac0644db14ae93415a74aab45d2 100644
--- a/Control/AthenaConfiguration/python/AllConfigFlags.py
+++ b/Control/AthenaConfiguration/python/AllConfigFlags.py
@@ -44,7 +44,8 @@ def _createCfgFlags():
     acf.addFlag('Common.isOnline', False ) #  Job runs in an online environment (access only to resources available at P1) # former global.isOnline
     acf.addFlag('Common.useOnlineLumi', lambda prevFlags : prevFlags.Common.isOnline ) #  Use online version of luminosity. ??? Should just use isOnline?
     acf.addFlag('Common.doExpressProcessing', False)
-
+    acf.addFlag('Common.bunchCrossingSource', lambda prevFlags : "MC" if prevFlags.Input.isMC else "TrigConf") # what BunchCrossingTool should we use?
+    
     def _checkProject():
         import os
         if "AthSimulation_DIR" in os.environ:
diff --git a/LArCalorimeter/LArMonitoring/python/LArCollisionTimeMonAlg.py b/LArCalorimeter/LArMonitoring/python/LArCollisionTimeMonAlg.py
index 415c78c6cea08313f9aec6301df5e64762ea6b11..4cc50650d9900662b24e3120552f4d7984029b57 100644
--- a/LArCalorimeter/LArMonitoring/python/LArCollisionTimeMonAlg.py
+++ b/LArCalorimeter/LArMonitoring/python/LArCollisionTimeMonAlg.py
@@ -27,7 +27,7 @@ def LArCollisionTimeMonConfig(inputFlags):
 
     from TrigBunchCrossingTool.BunchCrossingTool import BunchCrossingTool
     # FIXME when bunch crossing tool config is improved
-    larCollTimeMonAlg.BunchCrossingTool = BunchCrossingTool("TrigConf" if not inputFlags.Input.isMC else "MC")
+    larCollTimeMonAlg.BunchCrossingTool = BunchCrossingTool(inputFlags.Common.bunchCrossingSource)
 
 
     collTimeGroup = helper.addGroup(