diff --git a/Simulation/G4Atlas/G4AtlasTests/share/test_AtlasG4_ParticleGun_electrons.py b/Simulation/G4Atlas/G4AtlasTests/share/test_AtlasG4_ParticleGun_electrons.py
index cd891fd2687d865afb6a41a3f58f2e9d8f43ab55..fe34f104f3c0efdf75042921f0e8c7c41ccdbd2d 100644
--- a/Simulation/G4Atlas/G4AtlasTests/share/test_AtlasG4_ParticleGun_electrons.py
+++ b/Simulation/G4Atlas/G4AtlasTests/share/test_AtlasG4_ParticleGun_electrons.py
@@ -101,6 +101,7 @@ job.G4TestAlg.SimTestTools += [CfgGetter.getPrivateTool("HECHitsTestTool", check
 from G4AtlasAlg.G4AtlasAlgConf import G4AtlasAlg
 g4AtlasAlg = G4AtlasAlg()
 g4AtlasAlg.RandomGenerator = "athena"
+g4AtlasAlg.InputTruthCollection='GEN_EVENT'
 from AthenaCommon.AppMgr import ServiceMgr
 from AthenaServices.AthenaServicesConf import AtRndmGenSvc
 atRndmGenSvc = AtRndmGenSvc()