diff --git a/ChangeLog b/ChangeLog
index d4a6965..9624691 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,8 +1,9 @@
-2019-01-09
+2019-03-06
 
         * Version 1.6.0 released
         ========================
 
+        Correct Nbgd computation in GCTAOnOffObservation for Non=0 (#2838)
         Improve OpenMP handling in GWcs::dir2pix (#2770)
         Add support for Fermi/LAT P8V3 response functions
         CTA background rates are now per ontime (#2758)
diff --git a/NEWS b/NEWS
index d113e84..486065f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,6 @@
 New Features and Important Changes in GammaLib 1.6.0
 
-9 January 2019
+6 March 2019
 
 
 1. Introduction
@@ -320,6 +320,9 @@ unit tests for that response functions were added.
 
 20. CTA interface
 -----------------
+A missing term was added in GCTAOnOffObservation::wstat_value for computation
+of the number of background counts in case that Non=0 (#2838).
+
 CTA background rates are now per ontime and not livetime. This makes the IRF
 background consistent with the cube background, and is also consistent with
 the open gamma data format (#2758).
diff --git a/doc/source/admin/release_history/1.6.rst b/doc/source/admin/release_history/1.6.rst
index 937ad36..4f86b05 100644
--- a/doc/source/admin/release_history/1.6.rst
+++ b/doc/source/admin/release_history/1.6.rst
@@ -19,6 +19,8 @@ In particular, this release provides:
 Bug fixes
 ---------
 
+* [`2838 <https://cta-redmine.irap.omp.eu/issues/2838>`_] -
+  Correct Nbgd computation in ``GCTAOnOffObservation`` for Non=0
 * [`2708 <https://cta-redmine.irap.omp.eu/issues/2708>`_] -
   Fix precision issue with ``GCTABackground3D`` Monte-Carlo simulations
 * [`2706 <https://cta-redmine.irap.omp.eu/issues/2706>`_] -
diff --git a/inst/cta/src/GCTAOnOffObservation.cpp b/inst/cta/src/GCTAOnOffObservation.cpp
index ed69bf4..3cff77a 100644
--- a/inst/cta/src/GCTAOnOffObservation.cpp
+++ b/inst/cta/src/GCTAOnOffObservation.cpp
@@ -1,7 +1,7 @@
 /***************************************************************************
  *          GCTAOnOffObservation.cpp - CTA On/Off observation class        *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2013-2018 by Chia-Chun Lu & Christoph Deil               *
+ *  copyright (C) 2013-2019 by Chia-Chun Lu & Christoph Deil               *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -3269,7 +3269,7 @@ double GCTAOnOffObservation::wstat_value(const double& non,
 
     // Special case non = 0
     else if (non == 0.0) {
-        nbgd        = 0;
+        nbgd        = noff / alphap1;
         nonpred     = ngam + alpharat * noff;
         logL        = ngam + noff * std::log(alphap1);
         dlogLdsky   = 1.0;