diff --git a/bind/G4Calo.py b/bind/G4Calo.py
index de03e66..ca9cce3 100644
--- a/bind/G4Calo.py
+++ b/bind/G4Calo.py
@@ -9,7 +9,7 @@ from IPython.display import Image, display
 
 class G4System(_G4System):
 
-    def run_visualize(self,particleSpec : str, minEnergy: float, maxEnergy:float = -1.):
+    def run_visualize(self,particleSpec : str, minEnergy_GeV: float, maxEnergy_GeV:float = -1.):
         if maxEnergy < 0:
             maxEnergy = minEnergy
         _G4System.run_visualize(self, particleSpec, minEnergy_GeV, maxEnergy_GeV)