diff --git a/sim/transport/steer/CbmGeant4Settings.h b/sim/transport/steer/CbmGeant4Settings.h
index 409172f3483f0cb2aea5efbc3716967db6095586..df3029345c1bc0691e2a09c1c685da0edef4cbab 100644
--- a/sim/transport/steer/CbmGeant4Settings.h
+++ b/sim/transport/steer/CbmGeant4Settings.h
@@ -83,7 +83,10 @@ private:
   std::vector<std::string> fG4Commands {"/process/optical/verbose 0",
                                         "/process/optical/defaults/cerenkov/setMaxPhotons 20",
                                         "/process/optical/defaults/cerenkov/setMaxBetaChange 0.1",
-                                        "/process/optical/setTrackSecondariesFirst Cerenkov false"};
+                                        "/process/optical/setTrackSecondariesFirst Cerenkov true",
+                                        "/process/optical/processActivation Cerenkov true",
+                                        "/process/optical/processActivation OpAbsorption true",
+                                        "/process/optical/processActivation OpBoundary true"};
 
   Int_t fMaxNumSteps {10000000};