diff --git a/include/aspect/free_surface.h b/include/aspect/free_surface.h
index 35d9379cd1c..03b10506e61 100644
--- a/include/aspect/free_surface.h
+++ b/include/aspect/free_surface.h
@@ -77,6 +77,12 @@ namespace aspect
        */
       void execute();
 
+      /**
+       * Called by Simulator::set_assemblers() to allow the FreeSurfaceHandler
+       * to register its assembler.
+       */
+      void set_assemblers();
+
       /**
        * Allocates and sets up the members of the FreeSurfaceHandler. This
        * is called by Simulator<dim>::setup_dofs()
diff --git a/include/aspect/simulator/assemblers/interface.h b/include/aspect/simulator/assemblers/interface.h
index 0c0a82eae5a..1ace50077a9 100644
--- a/include/aspect/simulator/assemblers/interface.h
+++ b/include/aspect/simulator/assemblers/interface.h
@@ -587,6 +587,12 @@ namespace aspect
     class Manager
     {
       public:
+
+        /**
+         * Reset the state of the manager and remove all Assemblers.
+         */
+        void reset ();
+
         /**
          * A vector of pointers containing all assemblers for the Stokes preconditioner.
          * These assemblers are called once per cell.
diff --git a/source/simulator/assemblers/interface.cc b/source/simulator/assemblers/interface.cc
index d9d6afb5c8c..18bb522a898 100644
--- a/source/simulator/assemblers/interface.cc
+++ b/source/simulator/assemblers/interface.cc
@@ -487,6 +487,16 @@ namespace aspect
     }
 
 
+    template <int dim>
+    void Manager<dim>::reset ()
+    {
+      stokes_preconditioner.clear();
+      stokes_system.clear();
+      stokes_system_on_boundary_face.clear();
+      advection_system.clear();
+      advection_system_on_boundary_face.clear();
+      advection_system_on_interior_face.clear();
+    }
 
     template <int dim>
     Manager<dim>::Properties::Properties ()
diff --git a/source/simulator/assembly.cc b/source/simulator/assembly.cc
index fe8573601e0..1f44b179dba 100644
--- a/source/simulator/assembly.cc
+++ b/source/simulator/assembly.cc
@@ -123,10 +123,12 @@ namespace aspect
   Simulator<dim>::
   set_assemblers ()
   {
+    // first let the manager delete all existing assemblers:
+    assemblers->reset();
+
     assemblers->advection_system_assembler_properties.resize(1+introspection.n_compositional_fields);
     assemblers->advection_system_assembler_on_face_properties.resize(1+introspection.n_compositional_fields);
 
-
     if (parameters.include_melt_transport)
       {
         aspect::Assemblers::MeltStokesPreconditioner<dim> *preconditioner = new aspect::Assemblers::MeltStokesPreconditioner<dim>();
@@ -359,7 +361,11 @@ namespace aspect
           }
       }
 
-    // allow other assemblers to add themselves or modify the existing ones by firing the signal
+    // Let the free surface add its assembler:
+    if (parameters.free_surface_enabled)
+      free_surface->set_assemblers();
+
+    // Finally allow other assemblers to add themselves or modify the existing ones by firing the signal
     this->signals.set_assemblers(*this, *assemblers);
 
     // ensure that all assembler objects have access to the SimulatorAccess
diff --git a/source/simulator/free_surface.cc b/source/simulator/free_surface.cc
index 903819e2172..65922ddffcd 100644
--- a/source/simulator/free_surface.cc
+++ b/source/simulator/free_surface.cc
@@ -134,7 +134,23 @@ namespace aspect
       free_surface_dof_handler (sim.triangulation)
   {
     parse_parameters(prm);
+  }
+
+  template <int dim>
+  FreeSurfaceHandler<dim>::~FreeSurfaceHandler ()
+  {
+    // Free the Simulator's mapping object, otherwise
+    // when the FreeSurfaceHandler gets destroyed,
+    // the mapping's reference to the mesh displacement
+    // vector will be invalid.
+    sim.mapping.reset();
+  }
+
+
 
+  template <int dim>
+  void FreeSurfaceHandler<dim>::set_assemblers()
+  {
     aspect::Assemblers::ApplyStabilization<dim> *surface_stabilization
       = new aspect::Assemblers::ApplyStabilization<dim>();
 
@@ -153,16 +169,6 @@ namespace aspect
         update_JxW_values);
   }
 
-  template <int dim>
-  FreeSurfaceHandler<dim>::~FreeSurfaceHandler ()
-  {
-    // Free the Simulator's mapping object, otherwise
-    // when the FreeSurfaceHandler gets destroyed,
-    // the mapping's reference to the mesh displacement
-    // vector will be invalid.
-    sim.mapping.reset();
-  }
-
   template <int dim>
   void FreeSurfaceHandler<dim>::declare_parameters(ParameterHandler &prm)
   {
diff --git a/source/simulator/solver_schemes.cc b/source/simulator/solver_schemes.cc
index 586f6a4aa60..8056e2ca0a6 100644
--- a/source/simulator/solver_schemes.cc
+++ b/source/simulator/solver_schemes.cc
@@ -528,7 +528,6 @@ namespace aspect
 
         if (nonlinear_iteration <= 1)
           {
-            assemblers.reset (new internal::Assembly::AssemblerLists<dim>());
             set_assemblers();
             compute_current_constraints ();
           }