diff --git a/regtest/basic/rt23/plumed.dat b/regtest/basic/rt23/plumed.dat
index 534a2b211fb601c71076f6c1e76a30b41a44c59f..6a4185dc57ccbd3aa9437219fd4b6562f2d74310 100644
--- a/regtest/basic/rt23/plumed.dat
+++ b/regtest/basic/rt23/plumed.dat
@@ -11,8 +11,8 @@ dsz: MATHEVAL ARG=ds.a,ds.b,ds.c,cc.az,cc.bz,cc.cz VAR=sa,sb,sc,ca,cb,cc FUNC=sa
 PRINT FILE=colvar ARG=dsx,dsy,dsz
 
 # this is to test forces
-RESTRAINT ARG=dc.x AT=0 KAPPA=0 SLOPE=1
+BIASVALUE ARG=dc.x
 # this should be equivalent
-#RESTRAINT ARG=dsx AT=0 KAPPA=0 SLOPE=1
+# BIASVALUE ARG=dsx