diff --git a/preprocessor/DynamicModel.cc b/preprocessor/DynamicModel.cc
index e95d926aa..5ea7aa8ac 100644
--- a/preprocessor/DynamicModel.cc
+++ b/preprocessor/DynamicModel.cc
@@ -2334,15 +2334,22 @@ DynamicModel::writeDynamicModel(ostream &DynamicOutput, bool use_dll, bool julia
     }
   else
     {
-      DynamicOutput << "function dynamic!(y, x, params, steady_state, it_, residual)" << endl
+      DynamicOutput << "function dynamic!(y::Vector{Float64}, x::Matrix{Float64}, "
+                    << "params::Vector{Float64}," << endl
+                    << "                  steady_state::Vector{Float64}, it_::Int, "
+                    << "residual::Vector{Float64})" << endl
                     << "#" << endl
                     << "# Model equations" << endl
                     << "#" << endl
-                    << "residual = zeros(" << nrows << ", 1);" << endl
+                    << "residual = zeros(" << nrows << ");" << endl
                     << model_output.str()
                     << model_eq_output.str()
                     << "end" << endl << endl
-                    << "function dynamic!(y, x, params, steady_state, it_, residual, g1)" << endl
+                    << "function dynamic!(y::Vector{Float64}, x::Matrix{Float64}, "
+                    << "params::Vector{Float64}," << endl
+                    << "                  steady_state::Vector{Float64}, it_::Int, "
+                    << "residual::Vector{Float64}," << endl
+                    << "                  g1::Matrix{Float64})" << endl
                     << "  dynamic!(y, x, params, steady_state, it_, residual)" << endl
                     << model_output.str()
                     << "  g1 = zeros(" << nrows << ", " << dynJacobianColsNbr << ");" << endl
@@ -2351,7 +2358,11 @@ DynamicModel::writeDynamicModel(ostream &DynamicOutput, bool use_dll, bool julia
                     << "  #" << endl
                     << jacobian_output.str()
                     << "end" << endl << endl
-                    << "function dynamic!(y, x, params, steady_state, it_, residual, g1, g2)" << endl
+                    << "function dynamic!(y::Vector{Float64}, x::Matrix{Float64}, "
+                    << "params::Vector{Float64}," << endl
+                    << "                  steady_state::Vector{Float64}, it_::Int, "
+                    << "residual::Vector{Float64}," << endl
+                    << "                  g1::Matrix{Float64}, g2::Matrix{Float64})" << endl
                     << "  dynamic!(y, x, params, steady_state, it_, residual, g1)" << endl
                     << "  #" << endl
                     << "  # Hessian matrix" << endl
@@ -2366,7 +2377,11 @@ DynamicModel::writeDynamicModel(ostream &DynamicOutput, bool use_dll, bool julia
 
       // Initialize g3 matrix
       DynamicOutput << "end" << endl << endl
-                    << "function dynamic!(y, x, params, steady_state, it_, residual, g1, g2, g3)" << endl
+                    << "function dynamic!(y::Vector{Float64}, x::Matrix{Float64}, "
+                    << "params::Vector{Float64}," << endl
+                    << "                  steady_state::Vector{Float64}, it_::Int, "
+                    << "residual::Vector{Float64}," << endl
+                    << "                  g1::Matrix{Float64}, g2::Matrix{Float64}, g3::Matrix{Float64})" << endl
                     << "  dynamic!(y, x, params, steady_state, it_, residual, g1, g2)" << endl
                     << "  #" << endl
                     << "  # Third order derivatives" << endl
diff --git a/preprocessor/StaticModel.cc b/preprocessor/StaticModel.cc
index 587354d59..a79925da3 100644
--- a/preprocessor/StaticModel.cc
+++ b/preprocessor/StaticModel.cc
@@ -1406,8 +1406,10 @@ StaticModel::writeStaticModel(ostream &StaticOutput, bool use_dll, bool julia) c
     }
   else
     {
-      StaticOutput << "function static!(y, x, params, residual)" << endl
-                   << "residual = zeros( " << equations.size() << ", 1)" << endl
+      StaticOutput << "function static!(y::Vector{Float64}, x::Matrix{Float64}, "
+                   << "params::Vector{Float64}," << endl
+                   << "                 residual::Vector{Float64})" << endl
+                   << "residual = zeros(" << equations.size() << ")" << endl
                    << "#" << endl
                    << "# Model equations" << endl
                    << "#" << endl
@@ -1417,7 +1419,9 @@ StaticModel::writeStaticModel(ostream &StaticOutput, bool use_dll, bool julia) c
                    << "  residual = real(residual)+imag(residual).^2;" << endl
                    << "end" << endl
                    << "end" << endl << endl
-                   << "function static!(y, x, params, residual, g1)" << endl
+                   << "function static!(y::Vector{Float64}, x::Matrix{Float64}, "
+                   << "params::Vector{Float64}," << endl
+                   << "                 residual::Vector{Float64}, g1::Matrix{Float64})" << endl
                    << "  static!(y, x, params, residual)" << endl
                    << model_output.str()
                    << "  g1 = zeros(" << equations.size() << ", " << symbol_table.endo_nbr() << ");" << endl
@@ -1429,7 +1433,10 @@ StaticModel::writeStaticModel(ostream &StaticOutput, bool use_dll, bool julia) c
                    << "    g1 = real(g1)+2*imag(g1);" << endl
                    << "  end" << endl
                    << "end" << endl << endl
-                   << "function static!(y, x, params, residual, g1, g2)" << endl
+                   << "function static!(y::Vector{Float64}, x::Matrix{Float64}, "
+                   << "params::Vector{Float64}," << endl
+                   << "                 residual::Vector{Float64}, g1::Matrix{Float64}, "
+                   << "g2::Matrix{Float64})" << endl
                    << "  static!(y, x, params, residual, g1)" << endl
                    << "  #" << endl
                    << "  # Hessian matrix" << endl
@@ -1446,7 +1453,11 @@ StaticModel::writeStaticModel(ostream &StaticOutput, bool use_dll, bool julia) c
 
       // Initialize g3 matrix
       StaticOutput << "end" << endl << endl
-                   << "function static!(y, x, params, residual, g1, g2, g3)" << endl
+                   << "function static!(y::Vector{Float64}, x::Matrix{Float64}, "
+                   << "params::Vector{Float64}," << endl
+                   << "                 residual::Vector{Float64}, g1::Matrix{Float64}, "
+                   << "g2::Matrix{Float64}," << endl
+                   << "                 g3::Matrix{Float64})" << endl
                    << "  static!(y, x, params, residual, g1, g2)" << endl
                    << "  #" << endl
                    << "  # Third order derivatives" << endl
diff --git a/preprocessor/SteadyStateModel.cc b/preprocessor/SteadyStateModel.cc
index f340fc422..1613893e4 100644
--- a/preprocessor/SteadyStateModel.cc
+++ b/preprocessor/SteadyStateModel.cc
@@ -129,7 +129,8 @@ SteadyStateModel::writeSteadyStateFile(const string &basename, bool ramsey_model
   else
     output << "module " << basename << "SteadyState2" << endl << endl
            << "export steady_state!" << endl << endl
-           << "function steady_state!(ys_, exo_, params)" << endl;
+           << "function steady_state!(ys_::Vector{Float64}, exo_::Vector{Float64}, "
+           << "params::Vector{Float64})" << endl;
 
   for (size_t i = 0; i < def_table.size(); i++)
     {