diff --git a/preprocessor/ExprNode.cc b/preprocessor/ExprNode.cc
index 3805c1a6e..8798d7967 100644
--- a/preprocessor/ExprNode.cc
+++ b/preprocessor/ExprNode.cc
@@ -308,6 +308,12 @@ NumConstNode::writeOutput(ostream &output, ExprNodeOutputType output_type,
     output << datatree.num_constants.get(id);
 }
 
+bool
+NumConstNode::containsExternalFunction() const
+{
+  return false;
+}
+
 double
 NumConstNode::eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException)
 {
@@ -571,6 +577,12 @@ VariableNode::collectTemporary_terms(const temporary_terms_t &temporary_terms, t
     datatree.local_variables_table[symb_id]->collectTemporary_terms(temporary_terms, temporary_terms_inuse, Curr_Block);
 }
 
+bool
+VariableNode::containsExternalFunction() const
+{
+  return false;
+}
+
 void
 VariableNode::writeOutput(ostream &output, ExprNodeOutputType output_type,
                           const temporary_terms_t &temporary_terms,
@@ -1714,6 +1726,12 @@ UnaryOpNode::collectTemporary_terms(const temporary_terms_t &temporary_terms, te
     arg->collectTemporary_terms(temporary_terms, temporary_terms_inuse, Curr_Block);
 }
 
+bool
+UnaryOpNode::containsExternalFunction() const
+{
+  return arg->containsExternalFunction();
+}
+
 void
 UnaryOpNode::writeOutput(ostream &output, ExprNodeOutputType output_type,
                          const temporary_terms_t &temporary_terms,
@@ -2885,6 +2903,13 @@ BinaryOpNode::collectTemporary_terms(const temporary_terms_t &temporary_terms, t
     }
 }
 
+bool
+BinaryOpNode::containsExternalFunction() const
+{
+  return arg1->containsExternalFunction()
+    || arg2->containsExternalFunction();
+}
+
 void
 BinaryOpNode::writeOutput(ostream &output, ExprNodeOutputType output_type,
                           const temporary_terms_t &temporary_terms,
@@ -3963,6 +3988,14 @@ TrinaryOpNode::collectTemporary_terms(const temporary_terms_t &temporary_terms,
     }
 }
 
+bool
+TrinaryOpNode::containsExternalFunction() const
+{
+  return arg1->containsExternalFunction()
+    || arg2->containsExternalFunction()
+    || arg3->containsExternalFunction();
+}
+
 void
 TrinaryOpNode::writeOutput(ostream &output, ExprNodeOutputType output_type,
                            const temporary_terms_t &temporary_terms,
@@ -4626,6 +4659,12 @@ AbstractExternalFunctionNode::writePrhs(ostream &output, ExprNodeOutputType outp
     }
 }
 
+bool
+AbstractExternalFunctionNode::containsExternalFunction() const
+{
+  return true;
+}
+
 ExternalFunctionNode::ExternalFunctionNode(DataTree &datatree_arg,
                                            int symb_id_arg,
                                            const vector<expr_t> &arguments_arg) :
diff --git a/preprocessor/ExprNode.hh b/preprocessor/ExprNode.hh
index b008333cd..0500ff6d5 100644
--- a/preprocessor/ExprNode.hh
+++ b/preprocessor/ExprNode.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2007-2014 Dynare Team
+ * Copyright (C) 2007-2015 Dynare Team
  *
  * This file is part of Dynare.
  *
@@ -187,6 +187,9 @@ public:
   */
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const = 0;
 
+  //! returns true if the expr node contains an external function
+  virtual bool containsExternalFunction() const = 0;
+
   //! Writes output of node (with no temporary terms and with "outside model" output type)
   void writeOutput(ostream &output) const;
 
@@ -441,6 +444,7 @@ public:
   };
   virtual void prepareForDerivation();
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
+  virtual bool containsExternalFunction() const;
   virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
   virtual void collectTemporary_terms(const temporary_terms_t &temporary_terms, temporary_terms_inuse_t &temporary_terms_inuse, int Curr_Block) const;
   virtual double eval(const eval_context_t &eval_context) const throw (EvalException, EvalExternalFunctionException);
@@ -486,6 +490,7 @@ public:
   VariableNode(DataTree &datatree_arg, int symb_id_arg, int lag_arg);
   virtual void prepareForDerivation();
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
+  virtual bool containsExternalFunction() const;
   virtual void collectDynamicVariables(SymbolType type_arg, set<pair<int, int> > &result) const;
   virtual void computeTemporaryTerms(map<expr_t, int> &reference_count,
                                      temporary_terms_t &temporary_terms,
@@ -552,6 +557,7 @@ public:
   virtual void prepareForDerivation();
   virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
+  virtual bool containsExternalFunction() const;
   virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                            const temporary_terms_t &temporary_terms,
                                            deriv_node_temp_terms_t &tef_terms) const;
@@ -630,6 +636,7 @@ public:
   virtual int precedence(ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms) const;
   virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
+  virtual bool containsExternalFunction() const;
   virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                            const temporary_terms_t &temporary_terms,
                                            deriv_node_temp_terms_t &tef_terms) const;
@@ -724,6 +731,7 @@ public:
   virtual int precedence(ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms) const;
   virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const;
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const;
+  virtual bool containsExternalFunction() const;
   virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                            const temporary_terms_t &temporary_terms,
                                            deriv_node_temp_terms_t &tef_terms) const;
@@ -795,6 +803,7 @@ public:
   virtual void prepareForDerivation();
   virtual void computeTemporaryTerms(map<expr_t, int> &reference_count, temporary_terms_t &temporary_terms, bool is_matlab) const = 0;
   virtual void writeOutput(ostream &output, ExprNodeOutputType output_type, const temporary_terms_t &temporary_terms, deriv_node_temp_terms_t &tef_terms) const = 0;
+  virtual bool containsExternalFunction() const;
   virtual void writeExternalFunctionOutput(ostream &output, ExprNodeOutputType output_type,
                                            const temporary_terms_t &temporary_terms,
                                            deriv_node_temp_terms_t &tef_terms) const = 0;
diff --git a/preprocessor/StaticModel.cc b/preprocessor/StaticModel.cc
index 09fb9261b..045e63364 100644
--- a/preprocessor/StaticModel.cc
+++ b/preprocessor/StaticModel.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2003-2014 Dynare Team
+ * Copyright (C) 2003-2015 Dynare Team
  *
  * This file is part of Dynare.
  *
@@ -1927,9 +1927,16 @@ void StaticModel::writeAuxVarRecursiveDefinitions(const string &basename) const
          << "%           from model file (.mod)" << endl
          << endl;
 
+  deriv_node_temp_terms_t tef_terms;
+  temporary_terms_t temporary_terms;
+  for (int i = 0; i < (int) aux_equations.size(); i++)
+    if (dynamic_cast<ExprNode *>(aux_equations[i])->containsExternalFunction())
+      dynamic_cast<ExprNode *>(aux_equations[i])->writeExternalFunctionOutput(output, oMatlabStaticModel,
+                                                                              temporary_terms, tef_terms);
+
   for (int i = 0; i < (int) aux_equations.size(); i++)
     {
-      dynamic_cast<ExprNode *>(aux_equations[i])->writeOutput(output, oMatlabStaticModel);
+      dynamic_cast<ExprNode *>(aux_equations[i])->writeOutput(output, oMatlabStaticModel, temporary_terms, tef_terms);
       output << ";" << endl;
     }
 }