diff --git a/tracking/monitors/monitors.py b/tracking/monitors/monitors.py
index 116758daed333a64ad5d89a11bdd42c463aada51..1d66539280b71ec7c5c08db334155c1c2c345d0c 100644
--- a/tracking/monitors/monitors.py
+++ b/tracking/monitors/monitors.py
@@ -232,7 +232,7 @@ class Monitor(Element, metaclass=ABCMeta):
 class BunchMonitor(Monitor):
     """
     Monitor a single bunch and save attributes 
-    (mean, std, emit, current, and action).
+    (mean, std, emit, current, and cs_invariant).
     
     Parameters
     ----------