diff --git a/tracking/particles.py b/tracking/particles.py
index e16847f6a7975deb5feebe21df463005651b7e79..ee321bbe589c34aecdc9a05c6f1a68ab0d844c5f 100644
--- a/tracking/particles.py
+++ b/tracking/particles.py
@@ -472,11 +472,10 @@ class Beam:
             raise TypeError("{} should be bool or float64".format(filling_pattern.dtype))
                 
         self.bunch_list = bunch_list
+        self.update_filling_pattern()
         
         for bunch in self.not_empty:
             bunch.init_gaussian()
-            
-        self.update_filling_pattern()
     
     def update_filling_pattern(self):
         """Update the beam filling pattern."""