diff --git a/regtest/crystdistrib/rt-bops/colvar.reference b/regtest/crystdistrib/rt-bops/colvar.reference
index 75f0d872dd..c7f1e94b5c 100644
--- a/regtest/crystdistrib/rt-bops/colvar.reference
+++ b/regtest/crystdistrib/rt-bops/colvar.reference
@@ -1,4 +1,4 @@
 #! FIELDS time s
- 0.000000    10.66
- 0.025000   922.28
- 0.050000   993.43
+ 0.000000   925.50
+ 0.025000  1019.81
+ 0.050000  1064.21
diff --git a/regtest/crystdistrib/rt-bops/config b/regtest/crystdistrib/rt-bops/config
index 344183aa97..00a6231889 100644
--- a/regtest/crystdistrib/rt-bops/config
+++ b/regtest/crystdistrib/rt-bops/config
@@ -2,3 +2,11 @@ type=driver
 plumed_modules="adjmat crystdistrib"
 arg="--plumed plumed.dat --mf_xtc em.xtc --mc mcfile --timestep=0.001 --trajectory-stride=25"
 extra_files="../../trajectories/em.xtc" 
+
+function plumed_regtest_before() {
+   export PLUMED_FORBID_CHAINS=yes
+}
+
+function plumed_regtest_after() {
+   export PLUMED_FORBID_CHAINS=no
+}
diff --git a/regtest/crystdistrib/rt-bops/plumed.dat b/regtest/crystdistrib/rt-bops/plumed.dat
index 7249b9de3b..1c3d0191d2 100644
--- a/regtest/crystdistrib/rt-bops/plumed.dat
+++ b/regtest/crystdistrib/rt-bops/plumed.dat
@@ -260,6 +260,8 @@ ops: CUSTOM ARG=qp.i,qp.j,qp.k,c1.w VAR=i,j,k,d FUNC=((2.26628554234*exp(-(32.27
 
 ones: ONES SIZE=252
 
+cc: MATRIX_VECTOR_PRODUCT ARG=qp.i,ones
+PRINT ARG=cc FILE=cc FMT=%8.4f 
 
 sdot: MATRIX_VECTOR_PRODUCT ARG=ops,ones
 s: SUM ARG=sdot PERIODIC=NO