diff --git a/src/reference/ReferenceConfiguration.h b/src/reference/ReferenceConfiguration.h
index 2ea3779faa7a62b2d10949004ae2e74c2cf0e4e5..d92ac036b01cd19d49434cf73940b83642a88b9d 100644
--- a/src/reference/ReferenceConfiguration.h
+++ b/src/reference/ReferenceConfiguration.h
@@ -142,7 +142,7 @@ public:
   virtual double getReferenceArgument( const unsigned& i ){ plumed_error(); return 0.0; }
 /// These are overwritten in ReferenceArguments and ReferenceAtoms but are required here 
 /// to make PLMD::distance work
-  virtual const std::vector<Vector>& getReferencePositions()const;
+  virtual const std::vector<Vector>& getReferencePositions();
   virtual const std::vector<double>& getReferenceArguments(); 
   virtual const std::vector<double>& getReferenceMetric();
 /// These are overwritten in ReferenceArguments and ReferenceAtoms to make frame copying work
@@ -187,7 +187,7 @@ bool ReferenceConfiguration::parseVector(const std::string&key,std::vector<T>&t,
 }
 
 inline
-const std::vector<Vector>& ReferenceConfiguration::getReferencePositions()const{
+const std::vector<Vector>& ReferenceConfiguration::getReferencePositions(){
   return fake_refatoms;
 }