diff --git a/ChangeLog b/ChangeLog
index e41c05a..d0274ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,9 @@
-2016-10-17
+2016-11-10
 
         * Version 1.2.0 released
         ========================
 
+        Fix energy boundary handline in cssens (#1873)
         Add outcovmat parameter to ctlike (#1863)
         Add publish parameter and methods to ctobssim, ctselect, cslightcrv and csspec (#1871)
         Add csviscube script (#1853)
diff --git a/NEWS b/NEWS
index 29e3ee5..a758b89 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,6 @@
 New Features and Important Changes in ctools 1.2.0
 
-17 October 2016
+10 November 2016
 
 
 Introduction
@@ -213,6 +213,9 @@ a Sun constraint, but no Moon constraint (#1835).
 A publish() method has been added to cslightcrv and csspec that publishes the
 results on a VO hub (#1871).
 
+Fix energy boundary handling in cssens that has been corrupted during code
+refactoring (#1873).
+
 
 Examples
 --------
diff --git a/cscripts/cssens.py b/cscripts/cssens.py
index 9d99909..5d3a8b0 100755
--- a/cscripts/cssens.py
+++ b/cscripts/cssens.py
@@ -201,11 +201,11 @@ class cssens(ctools.cscript):
             Maximum energy
         """
         # Loop over all observations in container
-        for obs in self._obs:
+        for i, obs in enumerate(self._obs):
 
-            # Get observation energy boundaries
-            obs_ebounds = obs.events().ebounds()
-            
+            # Get energy boundaries of the observation
+            obs_ebounds = self._obs_ebounds[i]
+    
             # Get minimum and maximum energy of the observation
             obs_emin = obs_ebounds.emin()
             obs_emax = obs_ebounds.emax()
@@ -546,9 +546,10 @@ class cssens(ctools.cscript):
         # Get parameters
         self._get_parameters()
         
-        # Loop over observations and store ebounds
+        # Loop over observations and store a deep copy of the energy
+        # boundaries for later use
         for obs in self._obs:
-            self._obs_ebounds.append(obs.events().ebounds())
+            self._obs_ebounds.append(obs.events().ebounds().copy())
         
         # Initialise script
         colnames = ['loge', 'emin', 'emax', 'crab_flux', 'photon_flux',