diff --git a/lib/colvars/colvar.cpp b/lib/colvars/colvar.cpp
index 5e90636e1d..fcd7d57f06 100644
--- a/lib/colvars/colvar.cpp
+++ b/lib/colvars/colvar.cpp
@@ -846,7 +846,22 @@ void colvar::calc()
   if (cvm::debug())
     cvm::log("Collecting data from atom groups.\n");
 
+  // Update the enabled/disabled status of cvcs if necessary
+  if (cvc_flags.size()) {
+    bool any = false;
+    for (i = 0; i < cvcs.size(); i++) {
+      cvcs[i]->b_enabled = cvc_flags[i];
+      any = any || cvc_flags[i];
+    }
+    if (!any) {
+      cvm::error("ERROR: All CVCs are disabled for colvar " + this->name +"\n");
+      return;
+    }
+    cvc_flags.resize(0);
+  }
+
   for (i = 0; i < cvcs.size(); i++) {
+    if (!cvcs[i]->b_enabled) continue;
     for (ig = 0; ig < cvcs[i]->atom_groups.size(); ig++) {
       cvm::atom_group &atoms = *(cvcs[i]->atom_groups[ig]);
       atoms.reset_atoms_data();
@@ -1220,12 +1235,13 @@ void colvar::communicate_forces()
       return;
     }
 
+    int grad_index = 0; // index in the scripted gradients, to account for some components being disabled
     for (i = 0; i < cvcs.size(); i++) {
       if (!cvcs[i]->b_enabled) continue;
       cvm::increase_depth();
       // cvc force is colvar force times colvar/cvc Jacobian
       // (vector-matrix product)
-      (cvcs[i])->apply_force(colvarvalue(f.as_vector() * func_grads[i],
+      (cvcs[i])->apply_force(colvarvalue(f.as_vector() * func_grads[grad_index++],
                              cvcs[i]->value().type()));
       cvm::decrease_depth();
     }
@@ -1258,20 +1274,13 @@ void colvar::communicate_forces()
 
 int colvar::set_cvc_flags(std::vector<bool> const &flags) {
 
-  size_t i;
   if (flags.size() != cvcs.size()) {
     cvm::error("ERROR: Wrong number of CVC flags provided.");
     return COLVARS_ERROR;
   }
-  bool e = false;
-  for (i = 0; i < cvcs.size(); i++) {
-    cvcs[i]->b_enabled = flags[i];
-    e = e || flags[i];
-  }
-  if (!e) {
-    cvm::error("ERROR: All CVCs are disabled for this colvar.");
-    return COLVARS_ERROR;
-  }
+  // We cannot enable or disable cvcs in the middle of a timestep or colvar evaluation sequence
+  // so we store the flags that will be enforced at the next call to calc()
+  cvc_flags = flags;
   return COLVARS_OK;
 }
 
diff --git a/lib/colvars/colvar.h b/lib/colvars/colvar.h
index 79b00c026b..8a3e40518a 100644
--- a/lib/colvars/colvar.h
+++ b/lib/colvars/colvar.h
@@ -514,6 +514,9 @@ protected:
   /// \brief Array of \link cvc \endlink objects
   std::vector<cvc *> cvcs;
 
+  /// \brief Flags to enable or disable cvcs at next colvar evaluation
+  std::vector<bool> cvc_flags;
+
   /// \brief Initialize the sorted list of atom IDs for atoms involved
   /// in all cvcs (called when enabling task_collect_gradients)
   void build_atom_list(void);
diff --git a/lib/colvars/colvargrid.cpp b/lib/colvars/colvargrid.cpp
index 6cc667b51c..e2e660b984 100644
--- a/lib/colvars/colvargrid.cpp
+++ b/lib/colvars/colvargrid.cpp
@@ -24,31 +24,6 @@ colvar_grid_count::colvar_grid_count(std::vector<colvar *>  &colvars,
   : colvar_grid<size_t>(colvars, def_count, 1)
 {}
 
-std::istream & colvar_grid_count::read_restart(std::istream &is)
-{
-  size_t const start_pos = is.tellg();
-  std::string key, conf;
-  if ((is >> key) && (key == std::string("grid_parameters"))) {
-    is.seekg(start_pos, std::ios::beg);
-    is >> colvarparse::read_block("grid_parameters", conf);
-    parse_params(conf);
-  } else {
-    cvm::log("Grid parameters are missing in the restart file, using those from the configuration.\n");
-    is.seekg(start_pos, std::ios::beg);
-  }
-  read_raw(is);
-  return is;
-}
-
-std::ostream & colvar_grid_count::write_restart(std::ostream &os)
-{
-  write_params(os);
-  write_raw(os);
-  return os;
-}
-
-
-
 colvar_grid_scalar::colvar_grid_scalar()
   : colvar_grid<cvm::real>(), samples(NULL), grad(NULL)
 {}
@@ -79,30 +54,6 @@ colvar_grid_scalar::~colvar_grid_scalar()
   }
 }
 
-std::istream & colvar_grid_scalar::read_restart(std::istream &is)
-{
-  size_t const start_pos = is.tellg();
-  std::string key, conf;
-  if ((is >> key) && (key == std::string("grid_parameters"))) {
-    is.seekg(start_pos, std::ios::beg);
-    is >> colvarparse::read_block("grid_parameters", conf);
-    parse_params(conf);
-  } else {
-    cvm::log("Grid parameters are missing in the restart file, using those from the configuration.\n");
-    is.seekg(start_pos, std::ios::beg);
-  }
-  read_raw(is);
-  return is;
-}
-
-std::ostream & colvar_grid_scalar::write_restart(std::ostream &os)
-{
-  write_params(os);
-  write_raw(os);
-  return os;
-}
-
-
 cvm::real colvar_grid_scalar::maximum_value() const
 {
   cvm::real max = data[0];
@@ -163,29 +114,6 @@ colvar_grid_gradient::colvar_grid_gradient(std::vector<colvar *> &colvars)
   : colvar_grid<cvm::real>(colvars, 0.0, colvars.size()), samples(NULL)
 {}
 
-std::istream & colvar_grid_gradient::read_restart(std::istream &is)
-{
-  size_t const start_pos = is.tellg();
-  std::string key, conf;
-  if ((is >> key) && (key == std::string("grid_parameters"))) {
-    is.seekg(start_pos, std::ios::beg);
-    is >> colvarparse::read_block("grid_parameters", conf);
-    parse_params(conf);
-  } else {
-    cvm::log("Grid parameters are missing in the restart file, using those from the configuration.\n");
-    is.seekg(start_pos, std::ios::beg);
-  }
-  read_raw(is);
-  return is;
-}
-
-std::ostream & colvar_grid_gradient::write_restart(std::ostream &os)
-{
-  write_params(os);
-  write_raw(os);
-  return os;
-}
-
 void colvar_grid_gradient::write_1D_integral(std::ostream &os)
 {
   cvm::real bin, min, integral;
diff --git a/lib/colvars/colvargrid.h b/lib/colvars/colvargrid.h
index 29d21feb35..ac192ed0ee 100644
--- a/lib/colvars/colvargrid.h
+++ b/lib/colvars/colvargrid.h
@@ -836,6 +836,32 @@ public:
 }
 
 
+  /// \brief Read grid entry in restart file
+  std::istream & read_restart(std::istream &is)
+  {
+    size_t const start_pos = is.tellg();
+    std::string key, conf;
+    if ((is >> key) && (key == std::string("grid_parameters"))) {
+      is.seekg(start_pos, std::ios::beg);
+      is >> colvarparse::read_block("grid_parameters", conf);
+      parse_params(conf);
+    } else {
+      cvm::log("Grid parameters are missing in the restart file, using those from the configuration.\n");
+      is.seekg(start_pos, std::ios::beg);
+    }
+    read_raw(is);
+    return is;
+  }
+
+  /// \brief Write grid entry in restart file
+  std::ostream & write_restart(std::ostream &os)
+  {
+    write_params(os);
+    write_raw(os);
+    return os;
+  }
+
+
 /// \brief Write the grid data without labels, as they are
 /// represented in memory
 /// \param buf_size Number of values per line
@@ -1106,12 +1132,6 @@ public:
     return new_data[address(ix) + imult];
   }
 
-  /// \brief Read the grid from a restart
-  std::istream & read_restart(std::istream &is);
-
-  /// \brief Write the grid to a restart
-  std::ostream & write_restart(std::ostream &os);
-
   /// \brief Get the value from a formatted output and transform it
   /// into the internal representation (it may have been rescaled or
   /// manipulated)
@@ -1240,12 +1260,6 @@ public:
     has_data = true;
   }
 
-  /// \brief Read the grid from a restart
-  std::istream & read_restart(std::istream &is);
-
-  /// \brief Write the grid to a restart
-  std::ostream & write_restart(std::ostream &os);
-
   /// \brief Return the highest value
   cvm::real maximum_value() const;
 
@@ -1343,12 +1357,6 @@ public:
   }
 
 
-  /// \brief Read the grid from a restart
-  std::istream & read_restart(std::istream &is);
-
-  /// \brief Write the grid to a restart
-  std::ostream & write_restart(std::ostream &os);
-
   /// Compute and return average value for a 1D gradient grid
   inline cvm::real average()
   {
diff --git a/lib/colvars/colvarmodule.h b/lib/colvars/colvarmodule.h
index e1d25b1d97..8fe92cea15 100644
--- a/lib/colvars/colvarmodule.h
+++ b/lib/colvars/colvarmodule.h
@@ -4,7 +4,7 @@
 #define COLVARMODULE_H
 
 #ifndef COLVARS_VERSION
-#define COLVARS_VERSION "2015-07-21"
+#define COLVARS_VERSION "2015-08-12"
 #endif
 
 #ifndef COLVARS_DEBUG