diff --git a/src/Particle/ParticleSet.h b/src/Particle/ParticleSet.h
index d222fdb4ba..2c23502190 100644
--- a/src/Particle/ParticleSet.h
+++ b/src/Particle/ParticleSet.h
@@ -478,8 +478,8 @@ class ParticleSet : public QMCTraits, public OhmmsElementBase, public PtclOnLatt
   ///return the address of the i-th properties
   inline const FullPrecRealType* restrict getPropertyBase(int i) const { return Properties[i]; }
 
-  inline void setTwist(SingleParticlePos& t) { myTwist = t; }
-  inline SingleParticlePos getTwist() const { return myTwist; }
+  inline void setTwist(const SingleParticlePos& t) { myTwist = t; }
+  inline const SingleParticlePos& getTwist() const { return myTwist; }
 
   /** Initialize particles around another ParticleSet
    * Used to initialize an electron ParticleSet by an ion ParticleSet
diff --git a/src/QMCWaveFunctions/TrialWaveFunction.h b/src/QMCWaveFunctions/TrialWaveFunction.h
index 3bf96c7af3..82dc265e2e 100644
--- a/src/QMCWaveFunctions/TrialWaveFunction.h
+++ b/src/QMCWaveFunctions/TrialWaveFunction.h
@@ -470,8 +470,8 @@ class TrialWaveFunction
 
   void evaluateRatiosAlltoOne(ParticleSet& P, std::vector<ValueType>& ratios);
 
-  void setTwist(std::vector<RealType> t) { myTwist = t; }
-  const std::vector<RealType> twist() { return myTwist; }
+  void setTwist(const std::vector<RealType>& t) { myTwist = t; }
+  const std::vector<RealType>& twist() const { return myTwist; }
 
   inline void setMassTerm(ParticleSet& P)
   {
diff --git a/src/QMCWaveFunctions/WaveFunctionFactory.cpp b/src/QMCWaveFunctions/WaveFunctionFactory.cpp
index 67e3df3e04..496bf76164 100644
--- a/src/QMCWaveFunctions/WaveFunctionFactory.cpp
+++ b/src/QMCWaveFunctions/WaveFunctionFactory.cpp
@@ -70,6 +70,7 @@ std::unique_ptr<TrialWaveFunction> WaveFunctionFactory::buildTWF(xmlNodePtr cur,
   SPOSetBuilderFactory sposet_builder_factory(myComm, targetPtcl, ptclPool);
 
   std::string vp_file_to_load;
+  std::vector<ParticleSet::RealType> tsts(3, 0.);
   cur = cur->children;
   while (cur != NULL)
   {
@@ -91,7 +92,6 @@ std::unique_ptr<TrialWaveFunction> WaveFunctionFactory::buildTWF(xmlNodePtr cur,
           attribs.add(hdfName, "name");
           if (hdfName == "twistAngle")
           {
-            std::vector<ParticleSet::RealType> tsts(3, 0);
             putContent(tsts, kcur);
             targetPsi->setTwist(tsts);
             foundtwist = true;
@@ -102,7 +102,8 @@ std::unique_ptr<TrialWaveFunction> WaveFunctionFactory::buildTWF(xmlNodePtr cur,
       if (!foundtwist)
       {
         //default twist is [0 0 0]
-        std::vector<ParticleSet::RealType> tsts(3, 0);
+        tsts.resize(3);
+        std::fill(std::begin(tsts), std::end(tsts), 0.);
         targetPsi->setTwist(tsts);
       }
     }