diff --git a/src/colvar/CS2Backbone.cpp b/src/colvar/CS2Backbone.cpp
index 385f516f6c667e9b03f9689518556c7df5a29830..9c433ef2a97fcb1fcb10361bb58060820a63c9b0 100644
--- a/src/colvar/CS2Backbone.cpp
+++ b/src/colvar/CS2Backbone.cpp
@@ -115,7 +115,7 @@ in NMR driven Metadynamics \cite Granata:2013dk:
 \verbatim
 whole: GROUP ATOMS=2612-2514:-1,961-1:-1,2466-962:-1,2513-2467:-1
 WHOLEMOLECULES ENTITY0=whole
-cs: CS2BACKBONE ATOMS=1-2612 NRES=176 DATA=../data/ TEMPLATE=template.pdb CAMSHIFT 
+cs: CS2BACKBONE ATOMS=1-2612 NRES=176 DATA=../data/ TEMPLATE=template.pdb CAMSHIFT NOPBC 
 metad: METAD ARG=cs HEIGHT=0.5 SIGMA=0.1 PACE=200 BIASFACTOR=10
 PRINT ARG=cs,metad.bias FILE=COLVAR STRIDE=100 
 \endverbatim