diff --git a/DDSim/DD4hepSimulation.py b/DDSim/DD4hepSimulation.py
index d26a7ad50c99fe3b5875a126b7bea12ca6492552..dde0460c329d0bafa2675d37096c038d6aaf903a 100644
--- a/DDSim/DD4hepSimulation.py
+++ b/DDSim/DD4hepSimulation.py
@@ -309,8 +309,10 @@ class DD4hepSimulation(object):
     kernel.registerGlobalAction(run1)
     kernel.runAction().add(run1)
 
-    # Configure I/O
+    # Configure the random seed, do it before the I/O because we might change the seed!
+    _rndm = self.random.initialize( DDG4, kernel, self.output.random )
 
+    # Configure I/O
     if self.outputFile.endswith(".slcio"):
       lcOut = simple.setupLCIOOutput('LcioOutput', self.outputFile)
       lcOut.RunHeader = self.__addParametersToRunHeader()
@@ -319,9 +321,6 @@ class DD4hepSimulation(object):
 
     actionList = []
 
-    ##configure the random seed
-    rndm = self.random.initialize( DDG4, kernel, self.output.random )
-
     if self.enableGun:
       gun = DDG4.GeneratorAction(kernel,"Geant4ParticleGun/"+"Gun")
       self.gun.setOptions( gun )