diff --git a/bind/G4Calo.py b/bind/G4Calo.py
index 5161415..de03e66 100644
--- a/bind/G4Calo.py
+++ b/bind/G4Calo.py
@@ -12,7 +12,7 @@ class G4System(_G4System):
     def run_visualize(self,particleSpec : str, minEnergy: float, maxEnergy:float = -1.):
         if maxEnergy < 0:
             maxEnergy = minEnergy
-        _G4System.run_visualize(self, particleSpec, minEnergy, maxEnergy)
+        _G4System.run_visualize(self, particleSpec, minEnergy_GeV, maxEnergy_GeV)
         self.displayEvent()
 
     def displayEvent(self):