diff --git a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkCore/python/SlimmingHelper.py b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkCore/python/SlimmingHelper.py
index 22acc77c344c5ff5f5e95103f3b187b781cf13dc..1300fdcf76fa6a4f0ad992cd62b9a4c0e52ddbd8 100644
--- a/PhysicsAnalysis/DerivationFramework/DerivationFrameworkCore/python/SlimmingHelper.py
+++ b/PhysicsAnalysis/DerivationFramework/DerivationFrameworkCore/python/SlimmingHelper.py
@@ -64,8 +64,9 @@ class lockable_list(list):
                 self.__dict__["_locked"] = True
 
 ###This Include builds some Truth Information needed by the smart slimming list
-if globalflags.DataSource()=='geant4':
-	from DerivationFrameworkMCTruth.MCTruthCommon import *
+# Commented out for 21.0 to avoid problems with DAOD_IDTRKVALID - see ATLASRECTS-3861
+#if globalflags.DataSource()=='geant4':
+#	from DerivationFrameworkMCTruth.MCTruthCommon import *
 
 
 def buildNamesAndTypes():