diff --git a/src/core/ActionWithMatrix.cpp b/src/core/ActionWithMatrix.cpp
index c67eb136ad..db6112dab0 100644
--- a/src/core/ActionWithMatrix.cpp
+++ b/src/core/ActionWithMatrix.cpp
@@ -98,20 +98,6 @@ void ActionWithMatrix::setupMatrixStore() {
   if( next_action_in_chain ) next_action_in_chain->setupMatrixStore();
 }
 
-int ActionWithMatrix::checkTaskIsActive( const unsigned& itask ) const {
-  int nm = getNumberOfMasks(); if( nm<0 ) return 1;
-
-  // This checks for matrices that are masking some elements
-  unsigned nargs = getNumberOfArguments();
-  if( nm==1 && getPntrToArgument(nargs-1)->getRank()==2 ) return 1;
-
-  for(unsigned j=nargs-nm; j<nargs; ++j) {
-    plumed_assert( getPntrToArgument(j)->getRank()==1 );
-    if( fabs(getPntrToArgument(j)->get(itask))>0 ) return 1;
-  }
-  return 0;
-}
-
 void ActionWithMatrix::calculate() {
   if( actionInChain() ) return ;
   // Update all the neighbour lists
diff --git a/src/core/ActionWithMatrix.h b/src/core/ActionWithMatrix.h
index 2141187d07..b5a870ba2c 100644
--- a/src/core/ActionWithMatrix.h
+++ b/src/core/ActionWithMatrix.h
@@ -60,8 +60,6 @@ class ActionWithMatrix : public ActionWithVector {
   virtual ~ActionWithMatrix();
 ///
   virtual bool isAdjacencyMatrix() const { return false; }
-///
-  virtual int checkTaskIsActive( const unsigned& itask ) const ;
 ///
   void getAllActionLabelsInMatrixChain( std::vector<std::string>& mylabels ) const override ;
 /// Get the first matrix in this chain
diff --git a/src/core/ActionWithVector.cpp b/src/core/ActionWithVector.cpp
index e820f46ec7..a7105c37a9 100644
--- a/src/core/ActionWithVector.cpp
+++ b/src/core/ActionWithVector.cpp
@@ -436,12 +436,34 @@ void ActionWithVector::prepare() {
 }
 
 int ActionWithVector::checkTaskIsActive( const unsigned& itask ) const {
-  for(unsigned i=0; i<getNumberOfArguments(); ++i) {
-    Value* myarg = getPntrToArgument(i);
-    if( myarg->getRank()==0 ) continue;
-    else if( myarg->getRank()==1 && !myarg->hasDerivatives() ) {
-      if( fabs(myarg->get(itask))>0 ) return 1;
-    } else plumed_merror("should not be in action " + getName() );
+  unsigned nargs = getNumberOfArguments();
+  if( nmask>0 ) {
+     for(unsigned j=nargs-nmask; j<nargs; ++j) {
+         Value* myarg = getPntrToArgument(j);
+         if( myarg->getRank()==1 && !myarg->hasDerivatives() ) {
+             if( fabs(myarg->get(itask))>0 ) return 1;
+         } else if( myarg->getRank()==2 && !myarg->hasDerivatives() ) {
+             unsigned ncol = myarg->getRowLength(itask);
+             unsigned base = itask*myarg->getNumberOfColumns();
+             for(unsigned k=0; k<ncol; ++k) {
+                 if( fabs(myarg->get(base+k,false))>0 ) return 1;
+             }
+         } else plumed_merror("only matrices and vectors should be used as masks"); 
+     }
+  } else {
+     for(unsigned i=0; i<nargs; ++i) {
+       Value* myarg = getPntrToArgument(i);
+       if( myarg->getRank()==0 ) continue;
+       else if( myarg->getRank()==1 && !myarg->hasDerivatives() ) {
+         if( fabs(myarg->get(itask))>0 ) return 1;
+       } else if( myarg->getRank()==2 && !myarg->hasDerivatives() ) {
+           unsigned ncol = myarg->getRowLength(itask);
+           unsigned base = itask*myarg->getNumberOfColumns();
+           for(unsigned k=0; k<ncol; ++k) {
+               if( fabs(myarg->get(base+k,false))>0 ) return 1;
+           }
+       } else plumed_merror("should not be in action " + getName() );
+     }
   }
   return -1;
 }
diff --git a/src/core/ActionWithVector.h b/src/core/ActionWithVector.h
index e783dec244..97fc7e17e2 100644
--- a/src/core/ActionWithVector.h
+++ b/src/core/ActionWithVector.h
@@ -99,6 +99,8 @@ class ActionWithVector:
   bool atomsWereRetrieved;
 /// This is used to build the argument store when we cannot use the chain
   unsigned reallyBuildArgumentStore( const unsigned& argstart );
+/// Determine if a particular task is active based on the values of the input argument
+  int checkTaskIsActive( const unsigned& itask ) const ; 
 protected:
 /// A vector that contains the start point for the argument derivatives
   std::vector<unsigned> arg_deriv_starts;
@@ -131,8 +133,6 @@ class ActionWithVector:
 /// Check if a mask has been set
   int getNumberOfMasks() const ;
   void calculateNumericalDerivatives(ActionWithValue* av) override;
-/// Determine if a particular task is active based on the values of the input argument
-  virtual int checkTaskIsActive( const unsigned& itask ) const ;
 /// Turn off the calculation of the derivatives during the forward pass through a calculation
   bool doNotCalculateDerivatives() const override ;
 /// Are we running this command in a chain
diff --git a/src/function/FunctionOfMatrix.h b/src/function/FunctionOfMatrix.h
index e356eccdde..8050347a5c 100644
--- a/src/function/FunctionOfMatrix.h
+++ b/src/function/FunctionOfMatrix.h
@@ -56,8 +56,6 @@ class FunctionOfMatrix : public ActionWithMatrix {
   void turnOnDerivatives() override;
 /// Get the number of derivatives for this action
   unsigned getNumberOfDerivatives() override ;
-/// Check if the task is active
-  int checkTaskIsActive( const unsigned& itask ) const override ;
 /// Resize the matrices
   void prepare() override ;
 /// This gets the number of columns
@@ -232,17 +230,6 @@ unsigned FunctionOfMatrix<T>::getNumberOfColumns() const {
   plumed_error(); return 0;
 }
 
-template <class T>
-int FunctionOfMatrix<T>::checkTaskIsActive( const unsigned& itask ) const {
-  const ActionWithVector* av=dynamic_cast<const ActionWithVector*>( getPntrToArgument(0)->getPntrToAction() );
-  unsigned status=1; if( av ) status = av->checkTaskIsActive( itask );
-  for(unsigned i=1; i<getNumberOfArguments(); ++i) {
-    const ActionWithVector* av=dynamic_cast<const ActionWithVector*>( getPntrToArgument(i)->getPntrToAction() );
-    if( av && status!=av->checkTaskIsActive( itask ) ) plumed_merror("this doesn't work");
-  }
-  return status;
-}
-
 template <class T>
 void FunctionOfMatrix<T>::setupForTask( const unsigned& task_index, std::vector<unsigned>& indices, MultiValue& myvals ) const {
   int ncols = -1, basemat=-1; bool redo=false;
diff --git a/src/matrixtools/MatrixTimesVector.cpp b/src/matrixtools/MatrixTimesVector.cpp
index addabc5a29..dc995f4372 100644
--- a/src/matrixtools/MatrixTimesVector.cpp
+++ b/src/matrixtools/MatrixTimesVector.cpp
@@ -46,7 +46,6 @@ class MatrixTimesVector : public ActionWithMatrix {
   unsigned getNumberOfColumns() const override { plumed_error(); }
   void getNumberOfStreamedDerivatives( unsigned& nderivatives, Value* stopat ) override ;
   unsigned getNumberOfDerivatives() override ;
-  int checkTaskIsActive( const unsigned& itask ) const override ;
   void prepare() override ;
   void performTask( const unsigned& task_index, MultiValue& myvals ) const override ;
   bool isInSubChain( unsigned& nder ) override { nder = arg_deriv_starts[0]; return true; }
@@ -169,19 +168,6 @@ void MatrixTimesVector::prepare() {
   std::vector<unsigned> shape(1); shape[0] = getPntrToArgument(0)->getShape()[0]; myval->setShape(shape);
 }
 
-int MatrixTimesVector::checkTaskIsActive( const unsigned& itask ) const {
-  if( getPntrToArgument(1)->getRank()==1 ) {
-    ActionWithMatrix* am=dynamic_cast<ActionWithMatrix*>( getPntrToArgument(0)->getPntrToAction() );
-    plumed_assert( am ); return am->checkTaskIsActive(itask);
-  } else {
-    unsigned n=getNumberOfArguments()-1;
-    for(unsigned i=0; i<n; ++i) {
-      ActionWithMatrix* am=dynamic_cast<ActionWithMatrix*>( getPntrToArgument(i)->getPntrToAction() );
-      plumed_assert( am ); if( am->checkTaskIsActive(itask)>0 ) return 1;
-    }
-  }
-}
-
 void MatrixTimesVector::getNumberOfStreamedDerivatives( unsigned& nderivatives, Value* stopat ) {
   if( actionInChain() ) { ActionWithVector::getNumberOfStreamedDerivatives( nderivatives, stopat ); return; }