diff --git a/src/crystallization/InterMolecularTorsions.cpp b/src/crystallization/InterMolecularTorsions.cpp
index 15467d658153c012529edcffa29532734cd0f5d7..9f57725e889862b9afb7dc5c6b6fda8f8d077ac2 100644
--- a/src/crystallization/InterMolecularTorsions.cpp
+++ b/src/crystallization/InterMolecularTorsions.cpp
@@ -39,7 +39,7 @@ Calculate torsions between axis of adjacent molecules
 namespace PLMD {
 namespace crystallization {
 
-class InterMolecularTorsions : public MultiColvarFunction {
+class InterMolecularTorsions : public multicolvar::MultiColvarFunction {
 private:
 /// The switching function that tells us if atoms are close enough together
   SwitchingFunction switchingFunction;
@@ -47,9 +47,9 @@ public:
   static void registerKeywords( Keywords& keys );
   explicit InterMolecularTorsions(const ActionOptions&);
 /// Do the stuff with the switching functions
-  double calculateWeight( const unsigned& taskCode, const double& weight, AtomValuePack& myatoms ) const ;
+  double calculateWeight( const unsigned& taskCode, const double& weight, multicolvar::AtomValuePack& myatoms ) const ;
 /// Actually do the calculation
-  double compute( const unsigned& tindex, AtomValuePack& myatoms ) const ;
+  double compute( const unsigned& tindex, multicolvar::AtomValuePack& myatoms ) const ;
 /// Is the variable periodic
   bool isPeriodic(){ return true; }
   void retrieveDomain( std::string& min, std::string& max ){ min="-pi"; max="+pi"; }
@@ -112,7 +112,7 @@ MultiColvarFunction(ao)
   readVesselKeywords();
 }
 
-double InterMolecularTorsions::calculateWeight( const unsigned& taskCode, const double& weight, AtomValuePack& myatoms ) const {
+double InterMolecularTorsions::calculateWeight( const unsigned& taskCode, const double& weight, multicolvar::AtomValuePack& myatoms ) const {
   Vector distance = getSeparation( myatoms.getPosition(0), myatoms.getPosition(1) );
   double dfunc, sw = switchingFunction.calculateSqr( distance.modulo2(), dfunc );
 
@@ -124,7 +124,7 @@ double InterMolecularTorsions::calculateWeight( const unsigned& taskCode, const
   return sw;
 }
 
-double InterMolecularTorsions::compute( const unsigned& tindex, AtomValuePack& myatoms ) const {
+double InterMolecularTorsions::compute( const unsigned& tindex, multicolvar::AtomValuePack& myatoms ) const {
    Vector v1, v2, dv1, dv2, dconn, conn = getSeparation( myatoms.getPosition(0), myatoms.getPosition(1) );
 
    // Retrieve vectors