diff --git a/mex/sources/k_order_perturbation/dynamic_dll.cc b/mex/sources/k_order_perturbation/dynamic_dll.cc
index 5760b2960..ffc5649d4 100644
--- a/mex/sources/k_order_perturbation/dynamic_dll.cc
+++ b/mex/sources/k_order_perturbation/dynamic_dll.cc
@@ -22,13 +22,8 @@
 
 #include <sstream>
 
-/***********************************
- * Members of DynamicModelDLL for handling loading and calling
- * <model>_dynamic () function
- **************************************/
-DynamicModelDLL::DynamicModelDLL(const string &modName, const int y_length, const int j_cols,
-                                 const int n_max_lag, const int n_exog, const Vector &ySteady_arg, const string &sExt) throw (DynareException) :
-  length(y_length), jcols(j_cols), nMax_lag(n_max_lag), nExog(n_exog), ySteady(ySteady_arg)
+DynamicModelDLL::DynamicModelDLL(const string &modName, int nExog_arg, const string &sExt) throw (DynareException) :
+  nExog(nExog_arg)
 {
   string fName;
 #if !defined(__CYGWIN32__) && !defined(_WIN32)
@@ -94,59 +89,10 @@ DynamicModelDLL::~DynamicModelDLL()
 }
 
 void
-DynamicModelDLL::eval(double *y, double *x, int nb_row_x, double *params,
-                      int it_, double *residual, double *g1, double *g2, double *g3)
-{
-  double *steady_state = const_cast<double *>(ySteady.base());
-  Dynamic(y, x, nb_row_x, params, steady_state, it_, residual, g1, g2, g3);
-}
-
-void
-DynamicModelDLL::eval(const Vector &y, const TwoDMatrix &x, const  Vector *modParams,
-                      int it_, Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException)
-{
-  double  *dresidual, *dg1 = NULL, *dg2 = NULL, *dg3 = NULL;
-
-  if ((jcols-nExog) != y.length())
-    throw DynareException(__FILE__, __LINE__, "DLL Error: (jcols-nExog)!=ys.length()");
-
-  if (g1 != NULL)
-    {
-      if (g1->nrows() != length)
-        throw DynareException(__FILE__, __LINE__, "DLL Error: g1 has wrong size");
-      dg1 = const_cast<double *>(g1->base());
-    }
-  if (g2 != NULL)
-    dg2 = const_cast<double *>(g2->base());
-  dresidual = const_cast<double *>(residual.base());
-  if (g3 != NULL)
-    dg3 = const_cast<double *>(g3->base());
-  dresidual = const_cast<double *>(residual.base());
-  double *dy = const_cast<double *>(y.base());
-  double *dx = const_cast<double *>(x.base());
-  double *dbParams = const_cast<double *>(modParams->base());
-  double *steady_state = const_cast<double *>(ySteady.base());
-
-  Dynamic(dy, dx, nExog, dbParams, steady_state, it_, dresidual, dg1, dg2, dg3);
-}
-
-void
-DynamicModelDLL::eval(const Vector &y, const TwoDMatrix &x, const Vector *modParams,
+DynamicModelDLL::eval(const Vector &y, const Vector &x, const Vector &modParams, const Vector &ySteady,
                       Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException)
 {
-  eval(y, x, modParams, nMax_lag, residual, g1, g2, g3);
-}
-
-void
-DynamicModelDLL::eval(const Vector &y, const Vector &x, const Vector *modParams,
-                      Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException)
-{
-  /** ignore given exogens and create new 2D x matrix since
-   * when calling <model>_dynamic(z,x,params,it_) x must be equal to
-   * zeros(M_.maximum_lag+1,M_.exo_nbr)
-   **/
-  TwoDMatrix mx(nMax_lag+1, nExog);
-  mx.zeros(); // initialise shocks to 0s
-
-  eval(y, mx, modParams, nMax_lag, residual, g1, g2, g3);
+  Dynamic(y.base(), x.base(), nExog, modParams.base(), ySteady.base(), 0, residual.base(),
+          g1 == NULL ? NULL : g1->base(),
+          g2 == NULL ? NULL : g2->base(), g3 == NULL ? NULL : g3->base());
 }
diff --git a/mex/sources/k_order_perturbation/dynamic_dll.hh b/mex/sources/k_order_perturbation/dynamic_dll.hh
index efed398d9..3c1f34b8c 100644
--- a/mex/sources/k_order_perturbation/dynamic_dll.hh
+++ b/mex/sources/k_order_perturbation/dynamic_dll.hh
@@ -29,8 +29,8 @@
 #include "dynare_exception.h"
 
 // <model>_Dynamic DLL pointer
-typedef void  (*DynamicFn)
-(double *y, double *x, int nb_row_x, double *params, double *steady_state,
+typedef void (*DynamicFn)
+(const double *y, const double *x, int nb_row_x, const double *params, const double *steady_state,
  int it_, double *residual, double *g1, double *g2, double *g3);
 
 /**
@@ -40,13 +40,8 @@ typedef void  (*DynamicFn)
 class DynamicModelDLL
 {
 private:
-  DynamicFn  Dynamic; // pointer to the Dynamic function in DLL
-
-  const int length;  // tot num vars = Num of Jacobian rows
-  const int jcols;  // tot num var t-1, t and t+1 instances + exogs = Num of Jacobian columns
-  const int nMax_lag; // no of lags
+  DynamicFn Dynamic; // pointer to the Dynamic function in DLL
   const int nExog; // no of exogenous
-  const Vector &ySteady;
 #if defined(_WIN32) || defined(__CYGWIN32__)
   HINSTANCE dynamicHinstance;  // DLL instance pointer in Windows
 #else
@@ -55,17 +50,9 @@ private:
 
 public:
   // construct and load Dynamic model DLL
-  DynamicModelDLL(const string &fname, const int length, const int jcols,
-                  const int nMax_lag, const int nExog, const Vector &ySteady_arg, const string &sExt) throw (DynareException);
+  DynamicModelDLL(const string &fname, int nExog_arg, const string &sExt) throw (DynareException);
   virtual ~DynamicModelDLL();
 
-  // evaluate Dynamic model DLL
-  void eval(double *y, double *x, int nb_row_x, double *params,
-            int it_, double *residual, double *g1, double *g2, double *g3);
-  void eval(const Vector &y, const Vector &x,  const Vector *params,
-            Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException);
-  void eval(const Vector &y, const TwoDMatrix &x,  const Vector *params,
-            int it_, Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException);
-  void eval(const Vector &y, const TwoDMatrix &x,  const Vector *params,
+  void eval(const Vector &y, const Vector &x, const Vector &params, const Vector &ySteady,
             Vector &residual, TwoDMatrix *g1, TwoDMatrix *g2, TwoDMatrix *g3) throw (DynareException);
 };
diff --git a/mex/sources/k_order_perturbation/k_ord_dynare.cc b/mex/sources/k_order_perturbation/k_ord_dynare.cc
index feca54ab6..cce518db9 100644
--- a/mex/sources/k_order_perturbation/k_ord_dynare.cc
+++ b/mex/sources/k_order_perturbation/k_ord_dynare.cc
@@ -113,7 +113,7 @@ KordpDynare::calcDerivativesAtSteady() throw (DynareException)
   Vector llxSteady(nJcols-nExog);
   LLxSteady(ySteady, llxSteady);
 
-  dynamicDLL.eval(llxSteady, xx, &params, out, &g1, g2p, g3p);
+  dynamicDLL.eval(llxSteady, xx, params, ySteady, out, &g1, g2p, g3p);
 
   populateDerivativesContainer(g1, 1, JacobianIndices);
 
diff --git a/mex/sources/k_order_perturbation/k_order_perturbation.cc b/mex/sources/k_order_perturbation/k_order_perturbation.cc
index 2082a2472..1173e7514 100644
--- a/mex/sources/k_order_perturbation/k_order_perturbation.cc
+++ b/mex/sources/k_order_perturbation/k_order_perturbation.cc
@@ -134,9 +134,6 @@ extern "C" {
     const int nEndo = (int) mxGetScalar(mxFldp);
     mxFldp = mxGetField(M_, 0, "param_nbr");
     const int nPar = (int) mxGetScalar(mxFldp);
-    // it_ should be set to M_.maximum_lag
-    mxFldp = mxGetField(M_, 0, "maximum_lag");
-    const int nMax_lag = (int) mxGetScalar(mxFldp);
 
     nPred -= nBoth; // correct nPred for nBoth.
 
@@ -195,7 +192,7 @@ extern "C" {
         std::string jName(fName); //params.basename);
         jName += ".jnl";
         Journal journal(jName.c_str());
-        DynamicModelDLL dynamicDLL(fName, nEndo, jcols, nMax_lag, nExog, ySteady, dfExt);
+        DynamicModelDLL dynamicDLL(fName, nExog, dfExt);
 
         // intiate tensor library
         tls.init(kOrder, nStat+2*nPred+3*nBoth+2*nForw+nExog);