diff --git a/tracking/rf.py b/tracking/rf.py
index 08d52c6f3da95c26c7de5be511d7f80332387cf1..de05d591b9e3e6d57a4752619b3882c204ea354e 100644
--- a/tracking/rf.py
+++ b/tracking/rf.py
@@ -559,12 +559,11 @@ class CavityResonator():
     @Rs_per_cavity.setter
     def Rs_per_cavity(self, value):
         self._Rs_per_cavity = value
-        self._Rs = self.Rs_per_cavity * self.Ncav
 
     @property
     def Rs(self):
         """Shunt impedance [ohm]"""
-        return self._Rs
+        return self.Rs_per_cavity * self.Ncav
 
     @Rs.setter
     def Rs(self, value):