diff --git a/DDG4/python/DDSim/DD4hepSimulation.py b/DDG4/python/DDSim/DD4hepSimulation.py
index 5a8c7d7520eb7137f4e337090f478585d02c6a2c..133bde70a0116694c462238dd514c39bf7965b5a 100644
--- a/DDG4/python/DDSim/DD4hepSimulation.py
+++ b/DDG4/python/DDSim/DD4hepSimulation.py
@@ -646,6 +646,8 @@ SIM = DD4hepSimulation()
     if self.enableGun and ( self.enableG4Gun or self.enableG4GPS ):
       self._errorMessages.append("ERROR: Cannot use both DD4hepGun and Geant4 Gun or GeneralParticleSource")
 
+    if self.numberOfEvents < 0 and not self.inputFiles:
+      self._errorMessages.append("ERROR: Negative number of events only sensible for inputFiles")
 
   def _enablePrimaryHandler( self ):
     """ the geant4 Gun or GeneralParticleSource cannot be used together with the PrimaryHandler.